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/* realpath.c - Return the canonicalized absolute pathname */
/* Written 2000 by Werner Almesberger */
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <limits.h>
#include <errno.h>
#include <sys/stat.h>
/* FIXME: buffer overrun possible, loops forever on cyclic symlinks */
/*
* Canonical name: never ends with a slash
*/
static int resolve_path(char *path,char *result,char *pos)
{
if (*path == '/') {
*result = '/';
pos = result+1;
path++;
}
*pos = 0;
if (!*path) return 0;
while (1) {
char *slash;
struct stat st;
slash = *path ? strchr(path,'/') : NULL;
if (slash) *slash = 0;
if (!path[0] || (path[0] == '.' &&
(!path[1] || (path[1] == '.' && !path[2])))) {
pos--;
if (pos != result && path[0] && path[1])
while (*--pos != '/');
}
else {
strcpy(pos,path);
if (lstat(result,&st) < 0) return -1;
if (S_ISLNK(st.st_mode)) {
char buf[PATH_MAX];
if (readlink(result,buf,sizeof(buf)) < 0) return -1;
*pos = 0;
if (slash) {
*slash = '/';
strcat(buf,slash);
}
strcpy(path,buf);
if (*path == '/') result[1] = 0;
pos = strchr(result,0);
continue;
}
pos = strchr(result,0);
}
if (slash) {
*pos++ = '/';
path = slash+1;
}
*pos = 0;
if (!slash) break;
}
return 0;
}
char *realpath(const char *path,char *resolved_path)
{
char cwd[PATH_MAX];
char *path_copy;
int res;
if (!*path) {
errno = ENOENT; /* SUSv2 */
return NULL;
}
if (!getcwd(cwd,sizeof(cwd))) return NULL;
strcpy(resolved_path,"/");
if (resolve_path(cwd,resolved_path,resolved_path)) return NULL;
strcat(resolved_path,"/");
path_copy = strdup(path);
if (!path_copy) return NULL;
res = resolve_path(path_copy,resolved_path,strchr(resolved_path,0));
free(path_copy);
if (res) return NULL;
return resolved_path;
}
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