Add warn() and die()

Given slstatus is a tool that runs in the background, most likely run
from .xinitrc, it's important to prepend the name of the tool to error
messages so it becomes clear where the error is coming from.

To make this much more consistent, this commit adds warn() and die()
utility functions consistent with other suckless projects and adapts all
calls to fprintf(stderr, *) to the warn() and die() functions, greatly
increasing the readability of the code.

1 files changed, 3 insertions, 5 deletions

diff --git a/components/volume.c b/components/volume.c
index aa46446..8674211 100644
--- a/components/volume.c
+++ b/components/volume.c
@@ -21,21 +21,19 @@ vol_perc(const char *card)
 	char *vnames[] = SOUND_DEVICE_NAMES;
 
 	if ((afd = open(card, O_RDONLY | O_NONBLOCK)) < 0) {
-		fprintf(stderr, "open '%s': %s\n", card, strerror(errno));
+		warn("open '%s':", card);
 		return NULL;
 	}
 
 	if (ioctl(afd, (int)SOUND_MIXER_READ_DEVMASK, &devmask) < 0) {
-		fprintf(stderr, "ioctl 'SOUND_MIXER_READ_DEVMASK': %s\n",
-		        strerror(errno));
+		warn("ioctl 'SOUND_MIXER_READ_DEVMASK':");
 		close(afd);
 		return NULL;
 	}
 	for (i = 0; i < LEN(vnames); i++) {
 		if (devmask & (1 << i) && !strcmp("vol", vnames[i])) {
 			if (ioctl(afd, MIXER_READ(i), &v) < 0) {
-				fprintf(stderr, "ioctl 'MIXER_READ(%ld)': %s\n", i,
-				        strerror(errno));
+				warn("ioctl 'MIXER_READ(%ld)':", i);
 				close(afd);
 				return NULL;
 			}