/* Retrieve ELF / DWARF / source files from the debuginfod.

   Copyright (C) 2019-2020 Red Hat, Inc.

   This file is part of elfutils.

   This file is free software; you can redistribute it and/or modify

   it under the terms of either

     * the GNU Lesser General Public License as published by the Free

       Software Foundation; either version 3 of the License, or (at

       your option) any later version

   or

     * the GNU General Public License as published by the Free

       Software Foundation; either version 2 of the License, or (at

       your option) any later version

   or both in parallel, as here.

   elfutils is distributed in the hope that it will be useful, but

   WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   General Public License for more details.

   You should have received copies of the GNU General Public License and

   the GNU Lesser General Public License along with this program.  If

   not, see <http://www.gnu.org/licenses/>.  */

/* cargo-cult from libdwfl linux-kernel-modules.c */

/* In case we have a bad fts we include this before config.h because it

   can't handle _FILE_OFFSET_BITS.

   Everything we need here is fine if its declarations just come first.

   Also, include sys/types.h before fts. On some systems fts.h is not self

   contained. */

#ifdef BAD_FTS

  #include <sys/types.h>

  #include <fts.h>

#endif

#include "config.h"

#include "debuginfod.h"

#include "system.h"

#include <errno.h>

#include <stdlib.h>

/* We might be building a bootstrap dummy library, which is really simple. */

#ifdef DUMMY_LIBDEBUGINFOD

debuginfod_client *debuginfod_begin (void) { errno = ENOSYS; return NULL; }

int debuginfod_find_debuginfo (debuginfod_client *c, const unsigned char *b,

                               int s, char **p) { return -ENOSYS; }

int debuginfod_find_executable (debuginfod_client *c, const unsigned char *b,

                                int s, char **p) { return -ENOSYS; }

int debuginfod_find_source (debuginfod_client *c, const unsigned char *b,

                            int s, const char *f, char **p)  { return -ENOSYS; }

void debuginfod_set_progressfn(debuginfod_client *c,

			       debuginfod_progressfn_t fn) { }

void debuginfod_set_user_data (debuginfod_client *c, void *d) { }

void* debuginfod_get_user_data (debuginfod_client *c) { return NULL; }

const char* debuginfod_get_url (debuginfod_client *c) { return NULL; }

int debuginfod_add_http_header (debuginfod_client *c,

				const char *h) { return -ENOSYS; }

void debuginfod_end (debuginfod_client *c) { }

#else /* DUMMY_LIBDEBUGINFOD */

#include <assert.h>

#include <dirent.h>

#include <stdio.h>

#include <errno.h>

#include <unistd.h>

#include <fcntl.h>

#include <fts.h>

#include <regex.h>

#include <string.h>

#include <stdbool.h>

#include <linux/limits.h>

#include <time.h>

#include <utime.h>

#include <sys/syscall.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <sys/utsname.h>

#include <curl/curl.h>

/* If fts.h is included before config.h, its indirect inclusions may not

   give us the right LFS aliases of these functions, so map them manually.  */

#ifdef BAD_FTS

  #ifdef _FILE_OFFSET_BITS

    #define open open64

    #define fopen fopen64

  #endif

#else

  #include <sys/types.h>

  #include <fts.h>

#endif

struct debuginfod_client

{

  /* Progress/interrupt callback function. */

  debuginfod_progressfn_t progressfn;

  /* Stores user data. */

  void* user_data;

  /* Stores current/last url, if any. */

  char* url;

  /* Accumulates outgoing http header names/values. */

  int user_agent_set_p; /* affects add_default_headers */

  struct curl_slist *headers;

  /* Flags the default_progressfn having printed something that

     debuginfod_end needs to terminate. */

  int default_progressfn_printed_p;

  /* Can contain all other context, like cache_path, server_urls,

     timeout or other info gotten from environment variables, the

     handle data, etc. So those don't have to be reparsed and

     recreated on each request.  */

};

/* The cache_clean_interval_s file within the debuginfod cache specifies

   how frequently the cache should be cleaned. The file's st_mtime represents

   the time of last cleaning.  */

static const char *cache_clean_interval_filename = "cache_clean_interval_s";

static const time_t cache_clean_default_interval_s = 86400; /* 1 day */

/* The cache_max_unused_age_s file within the debuginfod cache specifies the

   the maximum time since last access that a file will remain in the cache.  */

static const char *cache_max_unused_age_filename = "max_unused_age_s";

static const time_t cache_default_max_unused_age_s = 604800; /* 1 week */

/* Location of the cache of files downloaded from debuginfods.

   The default parent directory is $HOME, or '/' if $HOME doesn't exist.  */

static const char *cache_default_name = ".debuginfod_client_cache";

static const char *cache_xdg_name = "debuginfod_client";

static const char *cache_path_envvar = DEBUGINFOD_CACHE_PATH_ENV_VAR;

/* URLs of debuginfods, separated by url_delim. */

static const char *server_urls_envvar = DEBUGINFOD_URLS_ENV_VAR;

static const char *url_delim =  " ";

static const char url_delim_char = ' ';

/* Timeout for debuginfods, in seconds (to get at least 100K). */

static const char *server_timeout_envvar = DEBUGINFOD_TIMEOUT_ENV_VAR;

static const long default_timeout = 90;

/* Data associated with a particular CURL easy handle. Passed to

   the write callback.  */

struct handle_data

{

  /* Cache file to be written to in case query is successful.  */

  int fd;

  /* URL queried by this handle.  */

  char url[PATH_MAX];

  /* This handle.  */

  CURL *handle;

  /* The client object whom we're serving. */

  debuginfod_client *client;

  /* Pointer to handle that should write to fd. Initially points to NULL,

     then points to the first handle that begins writing the target file

     to the cache. Used to ensure that a file is not downloaded from

     multiple servers unnecessarily.  */

  CURL **target_handle;

};

static size_t

debuginfod_write_callback (char *ptr, size_t size, size_t nmemb, void *data)

{

  ssize_t count = size * nmemb;

  struct handle_data *d = (struct handle_data*)data;

  /* Indicate to other handles that they can abort their transfer.  */

  if (*d->target_handle == NULL)

    {

      *d->target_handle = d->handle;

      /* update the client object */

      const char *url = NULL;

      (void) curl_easy_getinfo (d->handle, CURLINFO_EFFECTIVE_URL, &url;;

      if (url)

        {

          free (d->client->url);

          d->client->url = strdup(url); /* ok if fails */

        }

    }

  /* If this handle isn't the target handle, abort transfer.  */

  if (*d->target_handle != d->handle)

    return -1;

  return (size_t) write(d->fd, (void*)ptr, count);

}

/* Create the cache and interval file if they do not already exist.

   Return 0 if cache and config file are initialized, otherwise return

   the appropriate error code.  */

static int

debuginfod_init_cache (char *cache_path, char *interval_path, char *maxage_path)

{

  struct stat st;

  /* If the cache and config file already exist then we are done.  */

  if (stat(cache_path, &st) == 0 && stat(interval_path, &st) == 0)

    return 0;

  /* Create the cache and config files as necessary.  */

  if (stat(cache_path, &st) != 0 && mkdir(cache_path, 0777) < 0)

    return -errno;

  int fd = -1;

  /* init cleaning interval config file.  */

  fd = open(interval_path, O_CREAT | O_RDWR, 0666);

  if (fd < 0)

    return -errno;

  if (dprintf(fd, "%ld", cache_clean_default_interval_s) < 0)

    return -errno;

  /* init max age config file.  */

  if (stat(maxage_path, &st) != 0

      && (fd = open(maxage_path, O_CREAT | O_RDWR, 0666)) < 0)

    return -errno;

  if (dprintf(fd, "%ld", cache_default_max_unused_age_s) < 0)

    return -errno;

  return 0;

}

/* Delete any files that have been unmodied for a period

   longer than $DEBUGINFOD_CACHE_CLEAN_INTERVAL_S.  */

static int

debuginfod_clean_cache(debuginfod_client *c,

		       char *cache_path, char *interval_path,

		       char *max_unused_path)

{

  struct stat st;

  FILE *interval_file;

  FILE *max_unused_file;

  if (stat(interval_path, &st) == -1)

    {

      /* Create new interval file.  */

      interval_file = fopen(interval_path, "w");

      if (interval_file == NULL)

        return -errno;

      int rc = fprintf(interval_file, "%ld", cache_clean_default_interval_s);

      fclose(interval_file);

      if (rc < 0)

        return -errno;

    }

  /* Check timestamp of interval file to see whether cleaning is necessary.  */

  time_t clean_interval;

  interval_file = fopen(interval_path, "r");

  if (interval_file)

    {

      if (fscanf(interval_file, "%ld", &clean_interval) != 1)

        clean_interval = cache_clean_default_interval_s;

      fclose(interval_file);

    }

  else

    clean_interval = cache_clean_default_interval_s;

  if (time(NULL) - st.st_mtime < clean_interval)

    /* Interval has not passed, skip cleaning.  */

    return 0;

  /* Read max unused age value from config file.  */

  time_t max_unused_age;

  max_unused_file = fopen(max_unused_path, "r");

  if (max_unused_file)

    {

      if (fscanf(max_unused_file, "%ld", &max_unused_age) != 1)

        max_unused_age = cache_default_max_unused_age_s;

      fclose(max_unused_file);

    }

  else

    max_unused_age = cache_default_max_unused_age_s;

  char * const dirs[] = { cache_path, NULL, };

  FTS *fts = fts_open(dirs, 0, NULL);

  if (fts == NULL)

    return -errno;

  regex_t re;

  const char * pattern = ".*/[a-f0-9]+/(debuginfo|executable|source.*)$";

  if (regcomp (&re, pattern, REG_EXTENDED | REG_NOSUB) != 0)

    return -ENOMEM;

  FTSENT *f;

  long files = 0;

  while ((f = fts_read(fts)) != NULL)

    {

      /* ignore any files that do not match the pattern.  */

      if (regexec (&re, f->fts_path, 0, NULL, 0) != 0)

        continue;

      files++;

      if (c->progressfn) /* inform/check progress callback */

        if ((c->progressfn) (c, files, 0))

          break;

      switch (f->fts_info)

        {

        case FTS_F:

          /* delete file if max_unused_age has been met or exceeded.  */

          /* XXX consider extra effort to clean up old tmp files */

          if (time(NULL) - f->fts_statp->st_atime >= max_unused_age)

            unlink (f->fts_path);

          break;

        case FTS_DP:

          /* Remove if empty. */

          (void) rmdir (f->fts_path);

          break;

        default:

          ;

        }

    }

  fts_close (fts);

  regfree (&re);

  /* Update timestamp representing when the cache was last cleaned.  */

  utime (interval_path, NULL);

  return 0;

}

#define MAX_BUILD_ID_BYTES 64

static void

add_default_headers(debuginfod_client *client)

{

  if (client->user_agent_set_p)

    return;

  /* Compute a User-Agent: string to send.  The more accurately this

     describes this host, the likelier that the debuginfod servers

     might be able to locate debuginfo for us. */

  char* utspart = NULL;

  struct utsname uts;

  int rc = 0;

  rc = uname (&uts;;

  if (rc == 0)

    rc = asprintf(& utspart, "%s/%s", uts.sysname, uts.machine);

  if (rc < 0)

    utspart = NULL;

  FILE *f = fopen ("/etc/os-release", "r");

  if (f == NULL)

    f = fopen ("/usr/lib/os-release", "r");

  char *id = NULL;

  char *version = NULL;

  if (f != NULL)

    {

      while (id == NULL || version == NULL)

        {

          char buf[128];

          char *s = &buf[0];

          if (fgets (s, sizeof(buf), f) == NULL)

            break;

          int len = strlen (s);

          if (len < 3)

            continue;

          if (s[len - 1] == '\n')

            {

              s[len - 1] = '\0';

              len--;

            }

          char *v = strchr (s, '=');

          if (v == NULL || strlen (v) < 2)

            continue;

          /* Split var and value. */

          *v = '\0';

          v++;

          /* Remove optional quotes around value string. */

          if (*v == '"' || *v == '\'')

            {

              v++;

              s[len - 1] = '\0';

            }

          if (strcmp (s, "ID") == 0)

            id = strdup (v);

          if (strcmp (s, "VERSION_ID") == 0)

            version = strdup (v);

        }

      fclose (f);

    }

  char *ua = NULL;

  rc = asprintf(& ua, "User-Agent: %s/%s,%s,%s/%s",

                PACKAGE_NAME, PACKAGE_VERSION,

                utspart ?: "",

                id ?: "",

                version ?: "");

  if (rc < 0)

    ua = NULL;

  if (ua)

    (void) debuginfod_add_http_header (client, ua);

  free (ua);

  free (id);

  free (version);

  free (utspart);

}

#define xalloc_str(p, fmt, args...)        \

  do                                       \

    {                                      \

      if (asprintf (&p, fmt, args) < 0)    \

        {                                  \

          p = NULL;                        \

          rc = -ENOMEM;                    \

          goto out;                        \

        }                                  \

    } while (0)

/* Offer a basic form of progress tracing */

static int

default_progressfn (debuginfod_client *c, long a, long b)

{

  const char* url = debuginfod_get_url (c);

  int len = 0;

  /* We prefer to print the host part of the URL to keep the

     message short. */

  if (url != NULL)

    {

      const char* buildid = strstr(url, "buildid/");

      if (buildid != NULL)

        len = (buildid - url);

      else

        len = strlen(url);

    }

  if (b == 0 || url==NULL) /* early stage */

    dprintf(STDERR_FILENO,

            "\rDownloading %c", "-/|\\"[a % 4]);

  else if (b < 0) /* download in progress but unknown total length */

    dprintf(STDERR_FILENO,

            "\rDownloading from %.*s %ld",

            len, url, a);

  else /* download in progress, and known total length */

    dprintf(STDERR_FILENO,

            "\rDownloading from %.*s %ld/%ld",

            len, url, a, b);

  c->default_progressfn_printed_p = 1;

  return 0;

}

/* Query each of the server URLs found in $DEBUGINFOD_URLS for the file

   with the specified build-id, type (debuginfo, executable or source)

   and filename. filename may be NULL. If found, return a file

   descriptor for the target, otherwise return an error code.

*/

static int

debuginfod_query_server (debuginfod_client *c,

			 const unsigned char *build_id,

                         int build_id_len,

                         const char *type,

                         const char *filename,

                         char **path)

{

  char *server_urls;

  char *urls_envvar;

  char *cache_path = NULL;

  char *maxage_path = NULL;

  char *interval_path = NULL;

  char *target_cache_dir = NULL;

  char *target_cache_path = NULL;

  char *target_cache_tmppath = NULL;

  char suffix[PATH_MAX + 1]; /* +1 for zero terminator.  */

  char build_id_bytes[MAX_BUILD_ID_BYTES * 2 + 1];

  int rc;

  /* Clear the obsolete URL from a previous _find operation. */

  free (c->url);

  c->url = NULL;

  add_default_headers(c);

  /* Is there any server we can query?  If not, don't do any work,

     just return with ENOSYS.  Don't even access the cache.  */

  urls_envvar = getenv(server_urls_envvar);

  if (urls_envvar == NULL || urls_envvar[0] == '\0')

    {

      rc = -ENOSYS;

      goto out;

    }

  /* Copy lowercase hex representation of build_id into buf.  */

  if ((build_id_len >= MAX_BUILD_ID_BYTES) ||

      (build_id_len == 0 &&

       strlen ((const char *) build_id) > MAX_BUILD_ID_BYTES*2))

    return -EINVAL;

  if (build_id_len == 0) /* expect clean hexadecimal */

    strcpy (build_id_bytes, (const char *) build_id);

  else

    for (int i = 0; i < build_id_len; i++)

      sprintf(build_id_bytes + (i * 2), "%02x", build_id[i]);

  if (filename != NULL)

    {

      if (filename[0] != '/') // must start with /

        return -EINVAL;

      /* copy the filename to suffix, s,/,#,g */

      unsigned q = 0;

      for (unsigned fi=0; q < PATH_MAX-2; fi++) /* -2, escape is 2 chars.  */

        switch (filename[fi])

          {

          case '\0':

            suffix[q] = '\0';

            q = PATH_MAX-1; /* escape for loop too */

            break;

          case '/': /* escape / to prevent dir escape */

            suffix[q++]='#';

            suffix[q++]='#';

            break;

          case '#': /* escape # to prevent /# vs #/ collisions */

            suffix[q++]='#';

            suffix[q++]='_';

            break;

          default:

            suffix[q++]=filename[fi];

          }

      suffix[q] = '\0';

      /* If the DWARF filenames are super long, this could exceed

         PATH_MAX and truncate/collide.  Oh well, that'll teach

         them! */

    }

  else

    suffix[0] = '\0';

  /* set paths needed to perform the query

     example format

     cache_path:        $HOME/.cache

     target_cache_dir:  $HOME/.cache/0123abcd

     target_cache_path: $HOME/.cache/0123abcd/debuginfo

     target_cache_path: $HOME/.cache/0123abcd/source#PATH#TO#SOURCE ?

     $XDG_CACHE_HOME takes priority over $HOME/.cache.

     $DEBUGINFOD_CACHE_PATH takes priority over $HOME/.cache and $XDG_CACHE_HOME.

  */

  /* Determine location of the cache. The path specified by the debuginfod

     cache environment variable takes priority.  */

  char *cache_var = getenv(cache_path_envvar);

  if (cache_var != NULL && strlen (cache_var) > 0)

    xalloc_str (cache_path, "%s", cache_var);

  else

    {

      /* If a cache already exists in $HOME ('/' if $HOME isn't set), then use

         that. Otherwise use the XDG cache directory naming format.  */

      xalloc_str (cache_path, "%s/%s", getenv ("HOME") ?: "/", cache_default_name);

      struct stat st;

      if (stat (cache_path, &st) < 0)

        {

          char cachedir[PATH_MAX];

          char *xdg = getenv ("XDG_CACHE_HOME");

          if (xdg != NULL && strlen (xdg) > 0)

            snprintf (cachedir, PATH_MAX, "%s", xdg);

          else

            snprintf (cachedir, PATH_MAX, "%s/.cache", getenv ("HOME") ?: "/");

          /* Create XDG cache directory if it doesn't exist.  */

          if (stat (cachedir, &st) == 0)

            {

              if (! S_ISDIR (st.st_mode))

                {

                  rc = -EEXIST;

                  goto out;

                }

            }

          else

            {

              rc = mkdir (cachedir, 0700);

              /* Also check for EEXIST and S_ISDIR in case another client just

                 happened to create the cache.  */

              if (rc < 0

                  && (errno != EEXIST

                      || stat (cachedir, &st) != 0

                      || ! S_ISDIR (st.st_mode)))

                {

                  rc = -errno;

                  goto out;

                }

            }

          free (cache_path);

          xalloc_str (cache_path, "%s/%s", cachedir, cache_xdg_name);

        }

    }

  xalloc_str (target_cache_dir, "%s/%s", cache_path, build_id_bytes);

  xalloc_str (target_cache_path, "%s/%s%s", target_cache_dir, type, suffix);

  xalloc_str (target_cache_tmppath, "%s.XXXXXX", target_cache_path);

  /* XXX combine these */

  xalloc_str (interval_path, "%s/%s", cache_path, cache_clean_interval_filename);

  xalloc_str (maxage_path, "%s/%s", cache_path, cache_max_unused_age_filename);

  rc = debuginfod_init_cache(cache_path, interval_path, maxage_path);

  if (rc != 0)

    goto out;

  rc = debuginfod_clean_cache(c, cache_path, interval_path, maxage_path);

  if (rc != 0)

    goto out;

  /* If the target is already in the cache then we are done.  */

  int fd = open (target_cache_path, O_RDONLY);

  if (fd >= 0)

    {

      /* Success!!!! */

      if (path != NULL)

        *path = strdup(target_cache_path);

      rc = fd;

      goto out;

    }

  long timeout = default_timeout;

  const char* timeout_envvar = getenv(server_timeout_envvar);

  if (timeout_envvar != NULL)

    timeout = atoi (timeout_envvar);

  /* make a copy of the envvar so it can be safely modified.  */

  server_urls = strdup(urls_envvar);

  if (server_urls == NULL)

    {

      rc = -ENOMEM;

      goto out;

    }

  /* thereafter, goto out0 on error*/

  /* create target directory in cache if not found.  */

  struct stat st;

  if (stat(target_cache_dir, &st) == -1 && mkdir(target_cache_dir, 0700) < 0)

    {

      rc = -errno;

      goto out0;

    }

  /* NB: write to a temporary file first, to avoid race condition of

     multiple clients checking the cache, while a partially-written or empty

     file is in there, being written from libcurl. */

  fd = mkstemp (target_cache_tmppath);

  if (fd < 0)

    {

      rc = -errno;

      goto out0;

    }

  /* Count number of URLs.  */

  int num_urls = 0;

  for (int i = 0; server_urls[i] != '\0'; i++)

    if (server_urls[i] != url_delim_char

        && (i == 0 || server_urls[i - 1] == url_delim_char))

      num_urls++;

  CURLM *curlm = curl_multi_init();

  if (curlm == NULL)

    {

      rc = -ENETUNREACH;

      goto out0;

    }

  /* Tracks which handle should write to fd. Set to the first

     handle that is ready to write the target file to the cache.  */

  CURL *target_handle = NULL;

  struct handle_data *data = malloc(sizeof(struct handle_data) * num_urls);

  if (data == NULL)

    {

      rc = -ENOMEM;

      goto out0;

    }

  /* thereafter, goto out1 on error.  */

  /* Initalize handle_data with default values. */

  for (int i = 0; i < num_urls; i++)

    {

      data[i].handle = NULL;

      data[i].fd = -1;

    }

  char *strtok_saveptr;

  char *server_url = strtok_r(server_urls, url_delim, &strtok_saveptr);

  /* Initialize each handle.  */

  for (int i = 0; i < num_urls && server_url != NULL; i++)

    {

      data[i].fd = fd;

      data[i].target_handle = &target_handle;

      data[i].handle = curl_easy_init();

      data[i].client = c;

      if (data[i].handle == NULL)

        {

          rc = -ENETUNREACH;

          goto out1;

        }

      /* Build handle url. Tolerate both  http://foo:999  and

         http://foo:999/  forms */

      char *slashbuildid;

      if (strlen(server_url) > 1 && server_url[strlen(server_url)-1] == '/')

        slashbuildid = "buildid";

      else

        slashbuildid = "/buildid";

      if (filename) /* must start with / */

        snprintf(data[i].url, PATH_MAX, "%s%s/%s/%s%s", server_url,

                 slashbuildid, build_id_bytes, type, filename);

      else

        snprintf(data[i].url, PATH_MAX, "%s%s/%s/%s", server_url,

                 slashbuildid, build_id_bytes, type);

      curl_easy_setopt(data[i].handle, CURLOPT_URL, data[i].url);

      curl_easy_setopt(data[i].handle,

                       CURLOPT_WRITEFUNCTION,

                       debuginfod_write_callback);

      curl_easy_setopt(data[i].handle, CURLOPT_WRITEDATA, (void*)&data[i]);

      if (timeout > 0)

	{

	  /* Make sure there is at least some progress,

	     try to get at least 100K per timeout seconds.  */

	  curl_easy_setopt (data[i].handle, CURLOPT_LOW_SPEED_TIME,

			    timeout);

	  curl_easy_setopt (data[i].handle, CURLOPT_LOW_SPEED_LIMIT,

			    100 * 1024L);

	}

      curl_easy_setopt(data[i].handle, CURLOPT_FILETIME, (long) 1);

      curl_easy_setopt(data[i].handle, CURLOPT_FOLLOWLOCATION, (long) 1);

      curl_easy_setopt(data[i].handle, CURLOPT_FAILONERROR, (long) 1);

      curl_easy_setopt(data[i].handle, CURLOPT_NOSIGNAL, (long) 1);

#if LIBCURL_VERSION_NUM >= 0x072a00 /* 7.42.0 */

      curl_easy_setopt(data[i].handle, CURLOPT_PATH_AS_IS, (long) 1);

#else

      /* On old curl; no big deal, canonicalization here is almost the

         same, except perhaps for ? # type decorations at the tail. */

#endif

      curl_easy_setopt(data[i].handle, CURLOPT_AUTOREFERER, (long) 1);

      curl_easy_setopt(data[i].handle, CURLOPT_ACCEPT_ENCODING, "");

      curl_easy_setopt(data[i].handle, CURLOPT_HTTPHEADER, c->headers);

      curl_multi_add_handle(curlm, data[i].handle);

      server_url = strtok_r(NULL, url_delim, &strtok_saveptr);

    }

  /* Query servers in parallel.  */

  int still_running;

  long loops = 0;

  do

    {

      /* Wait 1 second, the minimum DEBUGINFOD_TIMEOUT.  */

      curl_multi_wait(curlm, NULL, 0, 1000, NULL);

      /* If the target file has been found, abort the other queries.  */

      if (target_handle != NULL)

        for (int i = 0; i < num_urls; i++)

          if (data[i].handle != target_handle)

            curl_multi_remove_handle(curlm, data[i].handle);

      CURLMcode curlm_res = curl_multi_perform(curlm, &still_running);

      if (curlm_res != CURLM_OK)

        {

          switch (curlm_res)

            {

            case CURLM_CALL_MULTI_PERFORM: continue;

            case CURLM_OUT_OF_MEMORY: rc = -ENOMEM; break;

            default: rc = -ENETUNREACH; break;

            }

          goto out1;

        }

      if (c->progressfn) /* inform/check progress callback */

        {

          loops ++;

          long pa = loops; /* default params for progress callback */

          long pb = 0; /* transfer_timeout tempting, but loops != elapsed-time */

          if (target_handle) /* we've committed to a server; report its download progress */

            {

              CURLcode curl_res;

#ifdef CURLINFO_SIZE_DOWNLOAD_T

              curl_off_t dl;

              curl_res = curl_easy_getinfo(target_handle,

                                           CURLINFO_SIZE_DOWNLOAD_T,

                                           &dl);

              if (curl_res == 0 && dl >= 0)

                pa = (dl > LONG_MAX ? LONG_MAX : (long)dl);

#else

              double dl;

              curl_res = curl_easy_getinfo(target_handle,

                                           CURLINFO_SIZE_DOWNLOAD,

                                           &dl);

              if (curl_res == 0)

                pa = (dl > LONG_MAX ? LONG_MAX : (long)dl);

#endif

              /* NB: If going through deflate-compressing proxies, this

                 number is likely to be unavailable, so -1 may show. */

#ifdef CURLINFO_CURLINFO_CONTENT_LENGTH_DOWNLOAD_T

              curl_off_t cl;

              curl_res = curl_easy_getinfo(target_handle,

                                           CURLINFO_CONTENT_LENGTH_DOWNLOAD_T,

                                           &cl);

              if (curl_res == 0 && cl >= 0)

                pb = (cl > LONG_MAX ? LONG_MAX : (long)cl);

#else

              double cl;

              curl_res = curl_easy_getinfo(target_handle,

                                           CURLINFO_CONTENT_LENGTH_DOWNLOAD,

                                           &cl);

              if (curl_res == 0)

                pb = (cl > LONG_MAX ? LONG_MAX : (long)cl);

#endif

            }

          if ((*c->progressfn) (c, pa, pb))

            break;

        }

    } while (still_running);

  /* Check whether a query was successful. If so, assign its handle

     to verified_handle.  */

  int num_msg;

  rc = -ENOENT;

  CURL *verified_handle = NULL;

  do

    {

      CURLMsg *msg;

      msg = curl_multi_info_read(curlm, &num_msg);

      if (msg != NULL && msg->msg == CURLMSG_DONE)

        {

          if (msg->data.result != CURLE_OK)

            {

              /* Unsucessful query, determine error code.  */

              switch (msg->data.result)

                {

                case CURLE_COULDNT_RESOLVE_HOST: rc = -EHOSTUNREACH; break; // no NXDOMAIN

                case CURLE_URL_MALFORMAT: rc = -EINVAL; break;

                case CURLE_COULDNT_CONNECT: rc = -ECONNREFUSED; break;

                case CURLE_PEER_FAILED_VERIFICATION: rc = -ECONNREFUSED; break;

                case CURLE_REMOTE_ACCESS_DENIED: rc = -EACCES; break;

                case CURLE_WRITE_ERROR: rc = -EIO; break;

                case CURLE_OUT_OF_MEMORY: rc = -ENOMEM; break;

                case CURLE_TOO_MANY_REDIRECTS: rc = -EMLINK; break;

                case CURLE_SEND_ERROR: rc = -ECONNRESET; break;

                case CURLE_RECV_ERROR: rc = -ECONNRESET; break;