Re: [uml-devel] [RFC][PATCH] include /usr/lib/uml in PATH

[Mattia Dongili <malattia@linux.it>]

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On Tue, Apr 04, 2006 at 02:39:44AM +0200, Blaisorblade wrote:
> On Sunday 02 April 2006 21:54, Mattia Dongili wrote:
[...]
> Thanks for the patch, we'll possibly apply it, but we need to reimplement (or 
> copy and fix from glibc) a two-phase execvp(). I've not done it because I've 
> felt unconfortable with the idea but it's the better I could think of for 
> now.

Hmm. I see.

> However, probably the patch can be merged anyway, or at least its idea...
[...]
> *) I'd agree with Geert, but you're indeed correct for that...
> *) Saying "19" gets a "NO"

I'm sorry... damn lazy programmers :)

> 
> #define UML_LIB_PATH ":/usr/lib/uml"

what about a config option instead? CONFIG_UML_NET_PATH

> 19 -> strlen(UML_LIB_PATH)
> in snprintf, "PATH=%s:/usr/lib/uml" -> "PATH=%s" UML_LIB_PATH
> 
> (using string literal concatenation)

here's an updated patch, I added a check for current PATH=="" to avoid
touching the PATH variable when empty (again, kind of keeping the same
behaviour of a clean execvp, I mean it makes no sense to append
/usr/lib/uml and not /bin:/usr/bin too).

Description:
append /usr/lib/uml to the existing PATH environment variable to let
execvp search uml_net in FHS compliant locations.

Signed-off-by: Mattia Dongili <malattia@linux.it>
-- 
mattia
:wq!

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diff --git a/arch/um/os-Linux/main.c b/arch/um/os-Linux/main.c
index 2878e89..774a3d7 100644
--- a/arch/um/os-Linux/main.c
+++ b/arch/um/os-Linux/main.c
@@ -74,6 +74,38 @@ static void last_ditch_exit(int sig)
 	exit(1);
 }
 
+#define UML_LIB_PATH	":/usr/lib/uml"
+
+static void setup_env_path(void) {
+	char *new_path = NULL;
+	char *old_path = NULL;
+	int path_len = 0;
+
+	old_path = getenv("PATH");
+	if (!old_path) {
+		/* if no PATH variable is set, just use
+		 * the default + /usr/lib/uml
+		 */
+		putenv("PATH=:/bin:/usr/bin/" UML_LIB_PATH);
+		return;
+	}
+
+	/* do nothing if the PATH variable exists but is empty */
+	path_len = strlen(old_path);
+	if (!path_len)
+		return;
+
+	/* append /usr/lib/uml to the existing path */
+	path_len += strlen("PATH=" UML_LIB_PATH) + 1;
+	new_path = malloc(path_len * sizeof(char));
+	if (!new_path) {
+		perror("coudn't malloc to set a new PATH");
+		return;
+	}
+	snprintf(new_path, path_len, "PATH=%s" UML_LIB_PATH, old_path);
+	putenv(new_path);
+}
+
 extern int uml_exitcode;
 
 extern void scan_elf_aux( char **envp);
@@ -114,6 +146,8 @@ int main(int argc, char **argv, char **e
 
 	set_stklim();
 
+	setup_env_path();
+
 	new_argv = malloc((argc + 1) * sizeof(char *));
 	if(new_argv == NULL){
 		perror("Mallocing argv");