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

[Mattia Dongili <malattia@linux.it>]

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On Fri, Apr 07, 2006 at 08:45:38AM +0200, Blaisorblade wrote:
> On Wednesday 05 April 2006 23:11, Mattia Dongili wrote:
> > On Tue, Apr 04, 2006 at 02:39:44AM +0200, Blaisorblade wrote:
[...]
> > > #define UML_LIB_PATH ":/usr/lib/uml"
> 
> > what about a config option instead? CONFIG_UML_NET_PATH
> 
> Don't think so, that's not supposed to be changed according to any config 
> option or I can't see that. Unless on 64-bit system that's /usr/lib64/uml, 
> and in that case it makes sense to have CONFIG_XXX = 
> "/usr/lib/uml" (without :, add them only in the source, i.e. insulate details 
> away).

Yes, that was what I meant. However it's probably not worth the effort
yet.

> > > 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).
> 
> In that case, you should append both IMHO - empty PATH and no PATH should be 
> treated the same way, I think.

updated patch attached, I hope you like the if-statement .

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..02cf668 100644
--- a/arch/um/os-Linux/main.c
+++ b/arch/um/os-Linux/main.c
@@ -74,6 +74,33 @@ 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 no PATH variable is set or it has an empty value
+	 * just use the default + /usr/lib/uml
+	 */
+	if (!old_path || (path_len = strlen(old_path)) == 0) {
+		putenv("PATH=:/bin:/usr/bin/" UML_LIB_PATH);
+		return;
+	}
+
+	/* append /usr/lib/uml to the existing path */
+	path_len += strlen("PATH=" UML_LIB_PATH) + 1;
+	new_path = malloc(path_len);
+	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 +141,8 @@ 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");