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authorLennart Poettering <lennart@poettering.net>2016-06-14 23:52:29 +0200
committerZbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>2016-06-14 17:52:29 -0400
commit69281c49eb824b2cc854fdb5b97f134b1371be8d (patch)
tree27049e3af27d4d8ab79440aabdaea4fc61df4ddb /src/basic/process-util.c
parent8dd57192bcee3c23625247ac8f11ef2043fcb36b (diff)
util-lib: rework get_process_cmdline() (#3529)
This reworks get_process_cmdline() quite substantially, fixing the following: - Fixes: https://github.com/systemd/systemd/pull/3512/commits/a4e3bf4d7ac2de51191ce136ee9361ba319e106c#r66837630 - The passed max_length is also applied to the "comm" name, if comm_fallback is set. - The right thing happens if max_length == 1 is specified - when the cmdline "foobar" is abbreviated to 6 characters the result is not "foobar" instead of "foo...". - trailing whitespace are removed before the ... suffix is appended. The 7 character abbreviation of "foo barz" is hence "foo..." instead of "foo ...". - leading whitespace are suppressed from the cmdline - a comprehensive test case is added
Diffstat (limited to 'src/basic/process-util.c')
-rw-r--r--src/basic/process-util.c90
1 files changed, 79 insertions, 11 deletions
diff --git a/src/basic/process-util.c b/src/basic/process-util.c
index 08fa98bb9e..b5b068ad38 100644
--- a/src/basic/process-util.c
+++ b/src/basic/process-util.c
@@ -110,6 +110,15 @@ int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char *
assert(line);
assert(pid >= 0);
+ /* Retrieves a process' command line. Replaces unprintable characters while doing so by whitespace (coalescing
+ * multiple sequential ones into one). If max_length is != 0 will return a string of the specified size at most
+ * (the trailing NUL byte does count towards the length here!), abbreviated with a "..." ellipsis. If
+ * comm_fallback is true and the process has no command line set (the case for kernel threads), or has a
+ * command line that resolves to the empty string will return the "comm" name of the process instead.
+ *
+ * Returns -ESRCH if the process doesn't exist, and -ENOENT if the process has no command line (and
+ * comm_fallback is false). */
+
p = procfs_file_alloca(pid, "cmdline");
f = fopen(p, "re");
@@ -119,12 +128,22 @@ int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char *
return -errno;
}
- if (max_length == 0) {
+ if (max_length == 1) {
+
+ /* If there's only room for one byte, return the empty string */
+ r = new0(char, 1);
+ if (!r)
+ return -ENOMEM;
+
+ *line = r;
+ return 0;
+
+ } else if (max_length == 0) {
size_t len = 0, allocated = 0;
while ((c = getc(f)) != EOF) {
- if (!GREEDY_REALLOC(r, allocated, len+2)) {
+ if (!GREEDY_REALLOC(r, allocated, len+3)) {
free(r);
return -ENOMEM;
}
@@ -136,7 +155,7 @@ int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char *
}
r[len++] = c;
- } else
+ } else if (len > 0)
space = true;
}
@@ -144,6 +163,7 @@ int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char *
r[len] = 0;
} else {
+ bool dotdotdot = false;
size_t left;
r = new(char, max_length);
@@ -155,28 +175,46 @@ int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char *
while ((c = getc(f)) != EOF) {
if (isprint(c)) {
+
if (space) {
- if (left <= 4)
+ if (left <= 2) {
+ dotdotdot = true;
break;
+ }
*(k++) = ' ';
left--;
space = false;
}
- if (left <= 4)
+ if (left <= 1) {
+ dotdotdot = true;
break;
+ }
*(k++) = (char) c;
left--;
- } else
+ } else if (k > r)
space = true;
}
- if (left <= 4) {
- size_t n = MIN(left-1, 3U);
- memcpy(k, "...", n);
- k[n] = 0;
+ if (dotdotdot) {
+ if (max_length <= 4) {
+ k = r;
+ left = max_length;
+ } else {
+ k = r + max_length - 4;
+ left = 4;
+
+ /* Eat up final spaces */
+ while (k > r && isspace(k[-1])) {
+ k--;
+ left++;
+ }
+ }
+
+ strncpy(k, "...", left-1);
+ k[left] = 0;
} else
*k = 0;
}
@@ -195,7 +233,37 @@ int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char *
if (h < 0)
return h;
- r = strjoin("[", t, "]", NULL);
+ if (max_length == 0)
+ r = strjoin("[", t, "]", NULL);
+ else {
+ size_t l;
+
+ l = strlen(t);
+
+ if (l + 3 <= max_length)
+ r = strjoin("[", t, "]", NULL);
+ else if (max_length <= 6) {
+
+ r = new(char, max_length);
+ if (!r)
+ return -ENOMEM;
+
+ memcpy(r, "[...]", max_length-1);
+ r[max_length-1] = 0;
+ } else {
+ char *e;
+
+ t[max_length - 6] = 0;
+
+ /* Chop off final spaces */
+ e = strchr(t, 0);
+ while (e > t && isspace(e[-1]))
+ e--;
+ *e = 0;
+
+ r = strjoin("[", t, "...]", NULL);
+ }
+ }
if (!r)
return -ENOMEM;
}