ext-toolchain-wrapper: fix paths if executable was resolved by PATH

If ext-toolchain-wrapper or any symbolic link to it was resolved by PATH, the wrapper takes the working directory to calculate the relative paths.

Now '/proc/self/exe' is used to resolve the absolute path to the toolchain directory if the wrapper was called neither with a relative nor an absolute path.

---
 toolchain/toolchain-external/ext-toolchain-wrapper.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

index 9a2fc70..e71a90a 100644
@@ -61,7 +61,7 @@ int main(int argc, char **argv)
 	char *relbasedir, *absbasedir;
 	char *progpath = argv[0];
 	char *basename;
-	int ret;
+	int ret, i, count = 0;
 
 	/* Calculate the relative paths */
 	basename = strrchr(progpath, '/');

@@ -77,7 +77,19 @@ int main(int argc, char **argv)
 		absbasedir = realpath(relbasedir, NULL);
 	} else {
 		basename = progpath;
-		absbasedir = realpath("../..", NULL);
+		absbasedir = malloc(PATH_MAX + 1);
+		ret = readlink("/proc/self/exe", absbasedir, PATH_MAX);
+		if (ret < 0) {
+			perror(__FILE__ ": readlink");
+			return 2;
+		}
+		for (i = ret; i > 0; i--) {
+			if ('/' == absbasedir[i]) {
+				absbasedir[i] = '\0';
+				if (3 == ++count)
+					break;
+			}
+		}
 	}
 	if (absbasedir == NULL) {
 		perror(__FILE__ ": realpath");

1.8.1.2


-- 
Dipl.-Inf. (FH) Patrick Ziegler

University Of Applied Sciences
Kaiserslautern

Amerikastrasse 1
D-66482 Zweibruecken
Germany

Phone:  +49 631 3724 5526
Mail:   patrick.ziegler at fh-kl.de
PGP KeyID 0xB4796B8C

http://www.fh-kl.de
http://www.fh-kl.de/fachbereiche/imst/iuk-knowhow.html

This patch saved my day and I could remove my own weird customizations to ext-toolchain-wrapper. Works like a charm, I'd like to see it integrated.

BR,
Lionel

Dear Patrick Ziegler,

This should be part of 2013.05 if it's not too late, since it fixes a real problem. My colleague Gregory (Cc'ed) was hit by the problem, and both of us confirmed that this patch is fixing the problem.

Best regards,

Thomas

Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

Patrick> If ext-toolchain-wrapper or any symbolic link to it was Patrick> resolved by PATH, the wrapper takes the working directory to Patrick> calculate the relative paths.

Patrick> Now '/proc/self/exe' is used to resolve the absolute path to Patrick> the toolchain directory if the wrapper was called neither with Patrick> a relative nor an absolute path.

Patrick> Signed-off-by: Patrick Ziegler <[email protected]> Patrick> ---

 Patrick>  toolchain/toolchain-external/ext-toolchain-wrapper.c | 16 ++++++++++++++--

Patrick> 1 file changed, 14 insertions(+), 2 deletions(-)

Patrick> diff --git a/toolchain/toolchain-external/ext-toolchain-wrapper.c b/toolchain/toolchain-external/ext-toolchain-wrapper.c Patrick> index 9a2fc70..e71a90a 100644
Patrick> --- a/toolchain/toolchain-external/ext-toolchain-wrapper.c
Patrick> +++ b/toolchain/toolchain-external/ext-toolchain-wrapper.c
Patrick> @@ -61,7 +61,7 @@ int main(int argc, char **argv)

 Patrick>  	char *relbasedir, *absbasedir;
 Patrick>  	char *progpath = argv[0];
 Patrick>  	char *basename;

Patrick> - int ret;
Patrick> + int ret, i, count = 0;

Patrick> /* Calculate the relative paths */
Patrick> basename = strrchr(progpath, '/');
Patrick> @@ -77,7 +77,19 @@ int main(int argc, char **argv)

 Patrick>  		absbasedir = realpath(relbasedir, NULL);
 Patrick>  	} else {
 Patrick>  		basename = progpath;

Patrick> - absbasedir = realpath("../..", NULL);
Patrick> + absbasedir = malloc(PATH_MAX + 1);
Patrick> + ret = readlink("/proc/self/exe", absbasedir, PATH_MAX);
Patrick> + if (ret < 0) {
Patrick> + perror(__FILE__ ": readlink");
Patrick> + return 2;
Patrick> + }

Patrick> + for (i = ret; i > 0; i--) {
Patrick> + if ('/' == absbasedir[i]) {

The output of readlink is NOT null terminated, so you end up accessing uninitialized data on the first iteration of this loop. I've fixed it by an explicit:

absbasedir[ret] = '\0';

In the rest of the file we don't do the reverse order checks (value == var), so I've swapped those.

The toolchain wrapper has unfortunately grown quite complicated since I've added it. I THINK we can simply always resolve /proc/self/exe and get rid of the conditional here, but as we're this close to the release I decided to apply your patch as it seems the safest option.

Committed, thanks.

Bye, Peter Korsgaard