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wmix: do not risk a crash (null-pointer-dereference) if $DISPLAY is not set

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The original code merely assumed that an XOpenDisplay failure was caused
only by incapacity to connect to the X server, but if $DISPLAY was not set
then the fprintf would be given a NULL pointer which it may not appreciate
(depending on the libc in use).
Let's avoid that case and try to provide more info to help the user.

Signed-off-by: Christophe CURIS <christophe.curis@free.fr>
This commit is contained in:
Christophe CURIS 2014-06-07 21:21:42 +02:00 committed by Carlos R. Mafra
parent 4be6166084
commit 2d191d0e6c
1 changed files with 14 additions and 2 deletions

16
wmix/wmix.c
View file

@ -161,8 +161,20 @@ int main(int argc, char **argv)
mixer_init(mixer_device, verbose, (const char **)exclude);
mixer_set_channel(0);
if ((display = XOpenDisplay(display_name)) == NULL) {
fprintf(stderr, "Unable to open display \"%s\"\n", display_name);
display = XOpenDisplay(display_name);
if (display == NULL) {
const char *name;
if (display_name) {
name = display_name;
} else {
name = getenv("DISPLAY");
if (name == NULL) {
fprintf(stderr, "wmix:error: Unable to open display, variable $DISPLAY not set\n");
return EXIT_FAILURE;
}
}
fprintf(stderr, "wmix:error: Unable to open display \"%s\"\n", name);
return EXIT_FAILURE;
}
display_width = (float)DisplayWidth(display, DefaultScreen(display)) / 4.0;