oss: Fix strncpy potentially truncating NULL out of the string

dos1 · SiegeLord · commit f9b979b93b10 · 2019-11-11T19:20:48.000-08:00
oss_audio_device is 512 characters long, so we can fill at most 511.
diff --git a/addons/audio/oss.c b/addons/audio/oss.c
@@ -161,7 +161,7 @@ static int oss_open_ver4()
 
       if (audioinfo.enabled) {
          if (strlen(audioinfo.devnode)) {
-            strncpy(oss_audio_device, audioinfo.devnode, 512);
+            strncpy(oss_audio_device, audioinfo.devnode, 511);
          }
          else if (audioinfo.legacy_device != -1) {
             sprintf(oss_audio_device, "/dev/dsp%i", audioinfo.legacy_device);
@@ -225,7 +225,7 @@ static int oss_open_ver3(void)
    }
 
    close(fd);
-   strncpy(oss_audio_device, oss_audio_device_ver3, 512);
+   strncpy(oss_audio_device, oss_audio_device_ver3, 511);
    ALLEGRO_INFO("Using device: %s\n", oss_audio_device);
 
    using_ver_4 = false;

Original file line number	Diff line number	Diff line change
`@@ -161,7 +161,7 @@ static int oss_open_ver4()`
`161`	`161`
`162`	`162`	`if (audioinfo.enabled) {`
`163`	`163`	`if (strlen(audioinfo.devnode)) {`
`164`		`- strncpy(oss_audio_device, audioinfo.devnode, 512);`
	`164`	`+ strncpy(oss_audio_device, audioinfo.devnode, 511);`
`165`	`165`	`}`
`166`	`166`	`else if (audioinfo.legacy_device != -1) {`
`167`	`167`	`sprintf(oss_audio_device, "/dev/dsp%i", audioinfo.legacy_device);`
`@@ -225,7 +225,7 @@ static int oss_open_ver3(void)`
`225`	`225`	`}`
`226`	`226`
`227`	`227`	`close(fd);`
`228`		`- strncpy(oss_audio_device, oss_audio_device_ver3, 512);`
	`228`	`+ strncpy(oss_audio_device, oss_audio_device_ver3, 511);`
`229`	`229`	`ALLEGRO_INFO("Using device: %s\n", oss_audio_device);`
`230`	`230`
`231`	`231`	`using_ver_4 = false;`