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49d9e06fb

Denys Vlasenko
Denys Vlasenko
2024-10-08
SUCCESS Duration: 160s

Subject

libbb: modify find_executable() to not temporarily write to PATH

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No binary (build failed)

Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

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Commit Diff GitHub →

debianutils/which.c +3 -6include/libbb.h +1 -1libbb/executable.c +30 -26shell/hush.c +14 -21
debianutils/which.c+3 -6
@@ -31,15 +31,12 @@
int which_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int which_main(int argc UNUSED_PARAM, char **argv)
{
- char *env_path;
+ const char *env_path;
int status = 0;
- /* This sizeof(): bb_default_root_path is shorter than BB_PATH_ROOT_PATH */
- char buf[sizeof(BB_PATH_ROOT_PATH)];
env_path = getenv("PATH");
if (!env_path)
- /* env_path must be writable, and must not alloc, so... */
- env_path = strcpy(buf, bb_default_root_path);
+ env_path = bb_default_root_path;
getopt32(argv, "^" "a" "\0" "-1"/*at least one arg*/);
argv += optind;
@@ -54,7 +51,7 @@ int which_main(int argc UNUSED_PARAM, char **argv)
puts(*argv);
}
} else {
- char *path;
+ const char *path;
char *p;
path = env_path;
include/libbb.h+1 -1
@@ -1227,7 +1227,7 @@ void FAST_FUNC update_utmp_DEAD_PROCESS(pid_t pid);
int file_is_executable(const char *name) FAST_FUNC;
-char *find_executable(const char *filename, char **PATHp) FAST_FUNC;
+char *find_executable(const char *filename, const char **PATHp) FAST_FUNC;
int executable_exists(const char *filename) FAST_FUNC;
/* BB_EXECxx always execs (it's not doing NOFORK/NOEXEC stuff),
libbb/executable.c+30 -26
@@ -21,14 +21,11 @@ int FAST_FUNC file_is_executable(const char *name)
/* search (*PATHp) for an executable file;
* return allocated string containing full path if found;
* PATHp points to the component after the one where it was found
- * (or NULL),
+ * (or NULL if found in last component),
* you may call find_executable again with this PATHp to continue
- * (if it's not NULL).
- * return NULL otherwise; (PATHp is undefined)
- * in all cases (*PATHp) contents are temporarily modified
- * but are restored on return (s/:/NUL/ and back).
+ * return NULL otherwise (PATHp is undefined)
*/
-char* FAST_FUNC find_executable(const char *filename, char **PATHp)
+char* FAST_FUNC find_executable(const char *name, const char **PATHp)
{
/* About empty components in $PATH:
* http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap08.html
@@ -38,38 +35,45 @@ char* FAST_FUNC find_executable(const char *filename, char **PATHp)
* initial colon preceding the rest of the list, or as a trailing colon
* following the rest of the list.
*/
- char *p, *n;
+ char *p = (char*) *PATHp;
- p = *PATHp;
- while (p) {
- int ex;
+ if (!p)
+ return NULL;
+ while (1) {
+ const char *end = strchrnul(p, ':');
+ int sz = end - p;
- n = strchr(p, ':');
- if (n) *n = '\0';
- p = concat_path_file(
- p[0] ? p : ".", /* handle "::" case */
- filename
- );
- ex = file_is_executable(p);
- if (n) *n++ = ':';
- if (ex) {
- *PATHp = n;
+ if (sz != 0) {
+ p = xasprintf("%.*s/%s", sz, p, name);
+ } else {
+ /* We have xxx::yyy in $PATH,
+ * it means "use current dir" */
+ p = xstrdup(name);
+// A bit of discrepancy wrt the path used if file is found here.
+// bash 5.2.15 "type" returns "./NAME".
+// GNU which v2.21 returns "/CUR/DIR/NAME".
+// With -a, both skip over all colons: xxx::::yyy is the same as xxx::yyy,
+// current dir is not tried the second time.
+ }
+ if (file_is_executable(p)) {
+ *PATHp = (*end ? end+1 : NULL);
return p;
}
free(p);
- p = n;
- } /* on loop exit p == NULL */
- return p;
+ if (*end == '\0')
+ return NULL;
+ p = (char *) end + 1;
+ }
}
/* search $PATH for an executable file;
* return 1 if found;
* return 0 otherwise;
*/
-int FAST_FUNC executable_exists(const char *filename)
+int FAST_FUNC executable_exists(const char *name)
{
- char *path = getenv("PATH");
- char *ret = find_executable(filename, &path);
+ const char *path = getenv("PATH");
+ char *ret = find_executable(name, &path);
free(ret);
return ret != NULL;
}
shell/hush.c+14 -21
@@ -8207,41 +8207,34 @@ static int setup_redirects(struct command *prog, struct squirrel **sqp)
//TODO: shares code with find_executable() in libbb, factor out?
static char *find_in_PATH(const char *name)
{
- char *ret;
- const char *PATH = get_local_var_value("PATH");
+ char *p = (char*) get_local_var_value("PATH");
- if (!PATH)
+ if (!p)
return NULL;
- ret = NULL;
while (1) {
- const char *end = strchrnul(PATH, ':');
- int sz = end - PATH; /* must be int! */
+ const char *end = strchrnul(p, ':');
+ int sz = end - p; /* must be int! */
- free(ret);
if (sz != 0) {
- ret = xasprintf("%.*s/%s", sz, PATH, name);
+ p = xasprintf("%.*s/%s", sz, p, name);
} else {
- /* We have xxx::yyyy in $PATH,
+ /* We have xxx::yyy in $PATH,
* it means "use current dir" */
- ret = xstrdup(name);
+ p = xstrdup(name);
}
- if (access(ret, F_OK) == 0)
- break;
-
- if (*end == '\0') {
- free(ret);
+ if (access(p, F_OK) == 0)
+ return p;
+ free(p);
+ if (*end == '\0')
return NULL;
- }
- PATH = end + 1;
+ p = (char *) end + 1;
}
-
- return ret;
}
#if ENABLE_HUSH_TYPE || ENABLE_HUSH_COMMAND
static char *find_executable_in_PATH(const char *name)
{
- char *PATH;
+ const char *PATH;
if (strchr(name, '/')) {
/* Name with '/' is tested verbatim, with no PATH traversal:
* "cd /bin; type ./cat" should print "./cat is ./cat",
@@ -8251,7 +8244,7 @@ static char *find_executable_in_PATH(const char *name)
return xstrdup(name);
return NULL;
}
- PATH = (char*)get_local_var_value("PATH");
+ PATH = get_local_var_value("PATH");
return find_executable(name, &PATH); /* path == NULL is ok */
}
#endif