Paul Smith wrote:
> Having PATH= be equivalent to PATH=., and even
> moreso "unset PATH" be equivalent to PATH=., is quite odd IMO.
It is just as odd as the fact that
PATH=:/bin is equivalent to PATH=.:/bin
and
PATH=/bin: is equivalent to PATH=/bin:.
> > > My personal opinion is that it's not difficult to come up with ways
> > > findprog can be useful _in addition_ to simply being a precursor to
> > > exec
> >
> > In this case we should probably add a flag argument that tells the
> > function to do the complete lookup also when the progname contains a
> > slash. For now, until someone claims that this functionality would
> > be actually useful, I'll leave it as is.
>
> I think this will not be needed. In the event that someone does need
> this they can simply use the findprog-in module instead.
That's not what I meant. Hope it's clearer with this patch (which I'll
push once savannah is working again).
2019-09-09 Bruno Haible <br...@clisp.org>
findprog-in: Make exec optimization optional.
* lib/findprog.h: Add double-inclusion guard. Include <stdbool.h>.
(find_in_given_path): Add optimize_for_exec parameter.
* lib/findprog-in.c (find_in_given_path): Likewise.
diff --git a/lib/findprog.h b/lib/findprog.h
index 9bc8a60..f7b4407 100644
--- a/lib/findprog.h
+++ b/lib/findprog.h
@@ -15,6 +15,10 @@
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
+#ifndef _FINDPROG_H
+#define _FINDPROG_H
+
+#include <stdbool.h>
#ifdef __cplusplus
extern "C" {
@@ -41,10 +45,16 @@ extern const char *find_in_path (const char *progname);
or relative to the current directory). The returned string can be used
with either execl/execv or execlp/execvp. It is freshly malloc()ed if it
is != PROGNAME.
- - Otherwise, it returns NULL. */
-extern const char *find_in_given_path (const char *progname, const char *path);
+ - Otherwise, it returns NULL.
+ If OPTIMIZE_FOR_EXEC is true, the function saves some work, under the
+ assumption that the resulting pathname will not be accessed directly,
+ only through execl/execv or execlp/execvp. */
+extern const char *find_in_given_path (const char *progname, const char *path,
+ bool optimize_for_exec);
#ifdef __cplusplus
}
#endif
+
+#endif /* _FINDPROG_H */
diff --git a/lib/findprog-in.c b/lib/findprog-in.c
index 3d70b7b..99b3c31 100644
--- a/lib/findprog-in.c
+++ b/lib/findprog-in.c
@@ -71,26 +71,84 @@ static const char * const suffixes[] =
};
const char *
-find_in_given_path (const char *progname, const char *path)
+find_in_given_path (const char *progname, const char *path,
+ bool optimize_for_exec)
{
{
bool has_slash = false;
- const char *p;
+ {
+ const char *p;
- for (p = progname; *p != '\0'; p++)
- if (ISSLASH (*p))
- {
- has_slash = true;
- break;
- }
+ for (p = progname; *p != '\0'; p++)
+ if (ISSLASH (*p))
+ {
+ has_slash = true;
+ break;
+ }
+ }
if (has_slash)
- /* If progname contains a slash, it is either absolute or relative to
- the current directory. PATH is not used.
- We could try the various suffixes and see whether one of the files
- with such a suffix is actually executable. But this is not needed,
- since the execl/execv/execlp/execvp functions will do these tests
- anyway. */
- return progname;
+ {
+ /* If progname contains a slash, it is either absolute or relative to
+ the current directory. PATH is not used. */
+ if (optimize_for_exec)
+ /* The execl/execv/execlp/execvp functions will try the various
+ suffixes anyway and fail if no executable is found. */
+ return progname;
+ else
+ {
+ /* Try the various suffixes and see whether one of the files
+ with such a suffix is actually executable. */
+ size_t i;
+ #if defined _WIN32 && !defined __CYGWIN__ /* Native Windows */
+ const char *progbasename;
+
+ {
+ const char *p;
+
+ progbasename = progname;
+ for (p = progname; *p != '\0'; p++)
+ if (ISSLASH (*p))
+ progbasename = p + 1;
+ }
+ #endif
+
+ /* Try all platform-dependent suffixes. */
+ for (i = 0; i < sizeof (suffixes) / sizeof (suffixes[0]); i++)
+ {
+ const char *suffix = suffixes[i];
+
+ #if defined _WIN32 && !defined __CYGWIN__ /* Native Windows */
+ /* File names without a '.' are not considered executable. */
+ if (*suffix != '\0' || strchr (progbasename, '.') != NULL)
+ #endif
+ {
+ /* Concatenate progname and suffix. */
+ char *progpathname =
+ xconcatenated_filename ("", progname, suffix);
+
+ /* On systems which have the eaccess() system call, let's
+ use it. On other systems, let's hope that this program
+ is not installed setuid or setgid, so that it is ok to
+ call access() despite its design flaw. */
+ if (eaccess (progpathname, X_OK) == 0)
+ {
+ /* Found! */
+ if (strcmp (progpathname, progname) == 0)
+ {
+ free (progpathname);
+ return progname;
+ }
+ else
+ return progpathname;
+ }
+
+ free (progpathname);
+ }
+ }
+
+ return NULL;
+ }
+ }
}
if (path == NULL)
@@ -131,14 +189,14 @@ find_in_given_path (const char *progname, const char
*path)
if (*suffix != '\0' || strchr (progname, '.') != NULL)
#endif
{
- /* Concatenate dir and progname. */
+ /* Concatenate dir, progname, and suffix. */
char *progpathname =
xconcatenated_filename (dir, progname, suffix);
- /* On systems which have the eaccess() system call, let's use
- it. On other systems, let's hope that this program is not
- installed setuid or setgid, so that it is ok to call
- access() despite its design flaw. */
+ /* On systems which have the eaccess() system call, let's
+ use it. On other systems, let's hope that this program
+ is not installed setuid or setgid, so that it is ok to
+ call access() despite its design flaw. */
if (eaccess (progpathname, X_OK) == 0)
{
/* Found! */
