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/*
* vim:ts=4:sw=4:expandtab
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdbool.h>
#include <stdint.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <dirent.h>
#include "i3status.h"
/*
* This function tries to automatically find out where i3status is being piped
* to and choses the appropriate output format.
*
* It is a little hackish but should work for most setups :).
*
* By iterating through /proc/<number>/stat and finding out the parent process
* id (just like pstree(1) or ps(1) work), we can get all children of our
* parent. When the output of i3status is being piped somewhere, the shell
* (parent process) spawns i3status and the destination process, so we will
* find our own process and the pipe target.
*
* We then check whether the pipe target’s name is known and chose the format.
*
*/
char *auto_detect_format() {
pid_t myppid = getppid();
pid_t mypid = getpid();
DIR *dir;
struct dirent *entry;
char path[255];
/* the relevant contents (for us) are:
* <pid> (<program name>) <status> <ppid>
* which should well fit into one page of 4096 bytes */
char buffer[4096];
char *format = NULL;
char *parentname = NULL;
if (!(dir = opendir("/proc")))
return NULL;
/* First pass: get the executable name of the parent.
* Upon error, we directly return NULL as we cannot continue without the
* name of our parent process. */
while ((entry = readdir(dir)) != NULL) {
pid_t pid = (pid_t)atoi(entry->d_name);
if (pid != myppid)
continue;
if (snprintf(path, sizeof(path), "/proc/%d/stat", pid) == -1 ||
!slurp(path, buffer, 4095))
goto out;
buffer[4095] = '\0';
char *leftbracket = strchr(buffer, '(');
char *rightbracket = strrchr(buffer, ')');
if (!leftbracket ||
!rightbracket ||
!(parentname = malloc((rightbracket - leftbracket))))
goto out;
*rightbracket = '\0';
strcpy(parentname, leftbracket + 1);
}
if (!parentname)
goto out;
/* Some shells, for example zsh, open a pipe in a way which will make the
* pipe target the parent process of i3status. If we detect that, we set
* the format and we are done. */
if (strcasecmp(parentname, "i3bar") == 0)
format = "none";
else if (strcasecmp(parentname, "dzen2") == 0)
format = "dzen2";
else if (strcasecmp(parentname, "xmobar") == 0)
format = "xmobar";
if (format)
goto out;
rewinddir(dir);
while ((entry = readdir(dir)) != NULL) {
pid_t pid = (pid_t)atoi(entry->d_name);
if (pid == 0 || pid == mypid)
continue;
if (snprintf(path, sizeof(path), "/proc/%d/stat", pid) == -1)
continue;
char *name = NULL;
pid_t ppid;
int loopcnt = 0;
/* Now we need to find out the name of the process.
* To avoid the possible race condition of the process existing already
* but not executing the destination (shell after fork() and before
* exec()), we check if the name equals its parent.
*
* We try this for up to 0.5 seconds, then we give up.
*/
do {
/* give the scheduler a chance between each iteration, don’t hog
* the CPU too much */
if (name)
usleep(50);
if (!slurp(path, buffer, 4095))
break;
buffer[4095] = '\0';
char *leftbracket = strchr(buffer, '(');
char *rightbracket = strrchr(buffer, ')');
if (!leftbracket ||
!rightbracket ||
sscanf(rightbracket + 2, "%*c %d", &ppid) != 1 ||
ppid != myppid)
break;
*rightbracket = '\0';
name = leftbracket + 1;
} while (strcmp(parentname, name) == 0 && loopcnt++ < 10000);
if (!name)
continue;
/* Check for known destination programs and set format */
char *newfmt = NULL;
if (strcasecmp(name, "i3bar") == 0)
newfmt = "none";
else if (strcasecmp(name, "dzen2") == 0)
newfmt = "dzen2";
else if (strcasecmp(name, "xmobar") == 0)
newfmt = "xmobar";
if (newfmt && format) {
fprintf(stderr, "i3status: cannot auto-configure, situation ambiguous (format \"%s\" *and* \"%s\" detected)\n", newfmt, format);
format = NULL;
break;
} else {
format = newfmt;
}
}
out:
if (parentname)
free(parentname);
closedir(dir);
return format;
}
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