/* -*- Mode: C -*- */
/* pathfind.c --- find a FILE MODE along PATH */
/* Author: Gary V Vaughan <gvaughan@oranda.demon.co.uk> */
/* Code: */
static char *
pathfind( char const * path,
char const * fname,
char const * mode );
#include "compat.h"
#ifndef HAVE_PATHFIND
#if defined(__windows__) && !defined(__CYGWIN__)
static char *
pathfind( char const * path,
char const * fname,
char const * mode )
{
return strdup(fname);
}
#else
static char * make_absolute(char const * string, char const * dot_path);
static char * canonicalize_pathname(char * path);
static char * extract_colon_unit(char * dir, char const * string, int * p_index);
/**
* local implementation of pathfind.
* @param[in] path colon separated list of directories
* @param[in] fname the name we are hunting for
* @param[in] mode the required file mode
* @returns an allocated string with the full path, or NULL
*/
static char *
pathfind( char const * path,
char const * fname,
char const * mode )
{
int p_index = 0;
int mode_bits = 0;
char * res_path = NULL;
char zPath[ AG_PATH_MAX + 1 ];
if (strchr( mode, 'r' )) mode_bits |= R_OK;
if (strchr( mode, 'w' )) mode_bits |= W_OK;
if (strchr( mode, 'x' )) mode_bits |= X_OK;
/*
* FOR each non-null entry in the colon-separated path, DO ...
*/
for (;;) {
DIR * dirP;
char * colon_unit = extract_colon_unit( zPath, path, &p_index );
if (colon_unit == NULL)
break;
dirP = opendir( colon_unit );
/*
* IF the directory is inaccessable, THEN next directory
*/
if (dirP == NULL)
continue;
for (;;) {
struct dirent *entP = readdir( dirP );
if (entP == (struct dirent *)NULL)
break;
/*
* IF the file name matches the one we are looking for, ...
*/
if (strcmp(entP->d_name, fname) == 0) {
char * abs_name = make_absolute(fname, colon_unit);
/*
* Make sure we can access it in the way we want
*/
if (access(abs_name, mode_bits) >= 0) {
/*
* We can, so normalize the name and return it below
*/
res_path = canonicalize_pathname(abs_name);
}
free(abs_name);
break;
}
}
closedir( dirP );
if (res_path != NULL)
break;
}
return res_path;
}
/*
* Turn STRING (a pathname) into an absolute pathname, assuming that
* DOT_PATH contains the symbolic location of `.'. This always returns
* a new string, even if STRING was an absolute pathname to begin with.
*/
static char *
make_absolute( char const * string, char const * dot_path )
{
char * result;
int result_len;
if (!dot_path || *string == '/') {
result = strdup( string );
} else {
if (dot_path && dot_path[0]) {
result = malloc( 2 + strlen( dot_path ) + strlen( string ) );
strcpy( result, dot_path );
result_len = (int)strlen(result);
if (result[result_len - 1] != '/') {
result[result_len++] = '/';
result[result_len] = '\0';
}
} else {
result = malloc( 3 + strlen( string ) );
result[0] = '.'; result[1] = '/'; result[2] = '\0';
result_len = 2;
}
strcpy( result + result_len, string );
}
return result;
}
/*
* Canonicalize PATH, and return a new path. The new path differs from
* PATH in that:
*
* Multiple `/'s are collapsed to a single `/'.
* Leading `./'s are removed.
* Trailing `/.'s are removed.
* Trailing `/'s are removed.
* Non-leading `../'s and trailing `..'s are handled by removing
* portions of the path.
*/
static char *
canonicalize_pathname( char *path )
{
int i, start;
char stub_char, *result;
/* The result cannot be larger than the input PATH. */
result = strdup( path );
stub_char = (*path == '/') ? '/' : '.';
/* Walk along RESULT looking for things to compact. */
i = 0;
while (result[i]) {
while (result[i] != '\0' && result[i] != '/')
i++;
start = i++;
/* If we didn't find any slashes, then there is nothing left to
* do.
*/
if (!result[start])
break;
/* Handle multiple `/'s in a row. */
while (result[i] == '/')
i++;
#if !defined (apollo)
if ((start + 1) != i)
#else
if ((start + 1) != i && (start != 0 || i != 2))
#endif /* apollo */
{
strcpy( result + start + 1, result + i );
i = start + 1;
}
/* Handle backquoted `/'. */
if (start > 0 && result[start - 1] == '\\')
continue;
/* Check for trailing `/', and `.' by itself. */
if ((start && !result[i])
|| (result[i] == '.' && !result[i+1])) {
result[--i] = '\0';
break;
}
/* Check for `../', `./' or trailing `.' by itself. */
if (result[i] == '.') {
/* Handle `./'. */
if (result[i + 1] == '/') {
strcpy( result + i, result + i + 1 );
i = (start < 0) ? 0 : start;
continue;
}
/* Handle `../' or trailing `..' by itself. */
if (result[i + 1] == '.' &&
(result[i + 2] == '/' || !result[i + 2])) {
while (--start > -1 && result[start] != '/')
;
memmove( result + start + 1, result + i + 2, strlen(result + i + 2) + 1 );
i = (start < 0) ? 0 : start;
continue;
}
}
}
if (!*result) {
*result = stub_char;
result[1] = '\0';
}
return result;
}
/*
* Given a string containing units of information separated by colons,
* return the next one pointed to by (P_INDEX), or NULL if there are no
* more. Advance (P_INDEX) to the character after the colon.
*/
static char *
extract_colon_unit(char * pzDir, char const * string, int * p_index)
{
char * pzDest = pzDir;
int ix = *p_index;
if (string == NULL)
return NULL;
if ((unsigned)ix >= strlen( string ))
return NULL;
{
char const * pzSrc = string + ix;
while (*pzSrc == ':') pzSrc++;
for (;;) {
char ch = (*(pzDest++) = *(pzSrc++));
switch (ch) {
case ':':
pzDest[-1] = NUL;
/* FALLTHROUGH */
case NUL:
goto copy_done;
}
if ((unsigned long)(pzDest - pzDir) >= AG_PATH_MAX)
break;
} copy_done:;
ix = (int)(pzSrc - string);
}
if (*pzDir == NUL)
return NULL;
*p_index = ix;
return pzDir;
}
#endif /* __windows__ / __CYGWIN__ */
#endif /* HAVE_PATHFIND */
/*
* Local Variables:
* mode: C
* c-file-style: "stroustrup"
* indent-tabs-mode: nil
* End:
* end of compat/pathfind.c */