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