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format detection: simplify code, handle "sh" processes in the hierarchy

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i3 starts processes using /bin/sh now, not $SHELL. This increases the
likelihood with which we are started by dash, which tends to leave its
processes in the hierarchy, e.g.:

michael       1524  i3bar --bar_id=bar-0 --socket=/run/user/1000/i3/ipc-s
michael       1525   \_ /bin/sh -c i3status
michael       1526       \_ i3status

This case is now handled correctly — when the parent is “sh”, the parent
of sh will be used instead.
This commit is contained in:
Michael Stapelberg 2013-11-09 14:34:12 +01:00
parent 31509b0d56
commit 14b43bdec2
1 changed files with 61 additions and 63 deletions
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124
src/auto_detect_format.c
View File

@ -14,6 +14,46 @@
#include "i3status.h"
/*
* Reads /proc/<pid>/stat and returns (via pointers) the name and parent pid of
* the specified pid.
* When false is returned, parsing failed and the contents of outname and
* outpid are undefined.
*
*/
static bool parse_proc_stat(pid_t pid, char **outname, pid_t *outppid) {
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];
if (snprintf(path, sizeof(path), "/proc/%d/stat", pid) == -1 ||
!slurp(path, buffer, sizeof(buffer)))
return false;
char *leftbracket = strchr(buffer, '(');
char *rightbracket = strrchr(buffer, ')');
if (!leftbracket ||
!rightbracket ||
sscanf(rightbracket + 2, "%*c %d", outppid) != 1)
return false;
*rightbracket = '\0';
*outname = strdup(leftbracket + 1);
return true;
}
static char *format_for_process(const char *name) {
if (strcasecmp(name, "i3bar") == 0)
return "i3bar";
else if (strcasecmp(name, "dzen2") == 0)
return "dzen2";
else if (strcasecmp(name, "xmobar") == 0)
return "xmobar";
else
return NULL;
}
/*
* This function tries to automatically find out where i3status is being piped
* to and choses the appropriate output format.
@ -40,68 +80,37 @@ char *auto_detect_format(void) {
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;
char *parentname;
pid_t parentpid;
if (!(dir = opendir("/proc")))
if (!parse_proc_stat(myppid, &parentname, &parentpid))
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 (strcmp(parentname, "sh") == 0) {
pid_t tmp_ppid = parentpid;
free(parentname);
fprintf(stderr, "i3status: auto-detection: parent process is \"sh\", looking at its parent\n");
if (!parse_proc_stat(tmp_ppid, &parentname, &parentpid))
return NULL;
}
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 = "i3bar";
else if (strcasecmp(parentname, "dzen2") == 0)
format = "dzen2";
else if (strcasecmp(parentname, "xmobar") == 0)
format = "xmobar";
if (format)
if ((format = format_for_process(parentname)) != NULL)
goto out;
rewinddir(dir);
if (!(dir = opendir("/proc")))
goto out;
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;
@ -115,34 +124,23 @@ char *auto_detect_format(void) {
do {
/* give the scheduler a chance between each iteration, don’t hog
* the CPU too much */
if (name)
if (name) {
usleep(50);
free(name);
}
if (!slurp(path, buffer, 4095))
if (!parse_proc_stat(pid, &name, &ppid))
break;
buffer[4095] = '\0';
char *leftbracket = strchr(buffer, '(');
char *rightbracket = strrchr(buffer, ')');
if (!leftbracket ||
!rightbracket ||
sscanf(rightbracket + 2, "%*c %d", &ppid) != 1 ||
ppid != myppid)
if (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 = "i3bar";
else if (strcasecmp(name, "dzen2") == 0)
newfmt = "dzen2";
else if (strcasecmp(name, "xmobar") == 0)
newfmt = "xmobar";
char *newfmt = format_for_process(name);
free(name);
if (newfmt && format && strcmp(newfmt, format) != 0) {
fprintf(stderr, "i3status: cannot auto-configure, situation ambiguous (format \"%s\" *and* \"%s\" detected)\n", newfmt, format);
@ -153,11 +151,11 @@ char *auto_detect_format(void) {
}
}
closedir(dir);
out:
if (parentname)
free(parentname);
closedir(dir);
return format;
}