util-lib: rework get_process_cmdline() (#3529)
This reworks get_process_cmdline() quite substantially, fixing the following:
- Fixes:
a4e3bf4d7a (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
This commit is contained in:
Lennart Poettering
Zbigniew Jędrzejewski-Szmek
parent
8dd57192bc
commit
69281c49eb
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@ -110,6 +110,15 @@ int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char *
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assert(line);
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assert(pid >= 0);
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/* Retrieves a process' command line. Replaces unprintable characters while doing so by whitespace (coalescing
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* multiple sequential ones into one). If max_length is != 0 will return a string of the specified size at most
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* (the trailing NUL byte does count towards the length here!), abbreviated with a "..." ellipsis. If
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* comm_fallback is true and the process has no command line set (the case for kernel threads), or has a
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* command line that resolves to the empty string will return the "comm" name of the process instead.
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*
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* Returns -ESRCH if the process doesn't exist, and -ENOENT if the process has no command line (and
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* comm_fallback is false). */
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p = procfs_file_alloca(pid, "cmdline");
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f = fopen(p, "re");
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@ -119,12 +128,22 @@ int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char *
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return -errno;
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}
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if (max_length == 0) {
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if (max_length == 1) {
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/* If there's only room for one byte, return the empty string */
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r = new0(char, 1);
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if (!r)
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return -ENOMEM;
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*line = r;
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return 0;
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} else if (max_length == 0) {
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size_t len = 0, allocated = 0;
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while ((c = getc(f)) != EOF) {
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if (!GREEDY_REALLOC(r, allocated, len+2)) {
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if (!GREEDY_REALLOC(r, allocated, len+3)) {
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free(r);
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return -ENOMEM;
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}
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@ -136,7 +155,7 @@ int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char *
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}
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r[len++] = c;
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} else
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} else if (len > 0)
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space = true;
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}
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@ -144,6 +163,7 @@ int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char *
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r[len] = 0;
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} else {
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bool dotdotdot = false;
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size_t left;
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r = new(char, max_length);
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@ -155,28 +175,46 @@ int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char *
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while ((c = getc(f)) != EOF) {
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if (isprint(c)) {
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if (space) {
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if (left <= 4)
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if (left <= 2) {
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dotdotdot = true;
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break;
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}
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*(k++) = ' ';
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left--;
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space = false;
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}
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if (left <= 4)
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if (left <= 1) {
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dotdotdot = true;
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break;
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}
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*(k++) = (char) c;
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left--;
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} else
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} else if (k > r)
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space = true;
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}
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if (left <= 4) {
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size_t n = MIN(left-1, 3U);
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memcpy(k, "...", n);
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k[n] = 0;
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if (dotdotdot) {
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if (max_length <= 4) {
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k = r;
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left = max_length;
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} else {
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k = r + max_length - 4;
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left = 4;
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/* Eat up final spaces */
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while (k > r && isspace(k[-1])) {
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k--;
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left++;
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}
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}
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strncpy(k, "...", left-1);
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k[left] = 0;
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} else
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*k = 0;
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}
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@ -195,7 +233,37 @@ int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char *
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if (h < 0)
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return h;
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r = strjoin("[", t, "]", NULL);
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if (max_length == 0)
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r = strjoin("[", t, "]", NULL);
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else {
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size_t l;
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l = strlen(t);
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if (l + 3 <= max_length)
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r = strjoin("[", t, "]", NULL);
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else if (max_length <= 6) {
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r = new(char, max_length);
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if (!r)
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return -ENOMEM;
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memcpy(r, "[...]", max_length-1);
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r[max_length-1] = 0;
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} else {
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char *e;
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t[max_length - 6] = 0;
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/* Chop off final spaces */
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e = strchr(t, 0);
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while (e > t && isspace(e[-1]))
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e--;
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*e = 0;
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r = strjoin("[", t, "...]", NULL);
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}
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}
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if (!r)
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return -ENOMEM;
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}
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@ -18,7 +18,10 @@
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <sched.h>
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#include <sys/mount.h>
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#include <sys/personality.h>
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#include <sys/prctl.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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@ -26,6 +29,7 @@
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#include "alloc-util.h"
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#include "architecture.h"
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#include "fd-util.h"
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#include "log.h"
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#include "macro.h"
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#include "parse-util.h"
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@ -59,7 +63,11 @@ static void test_get_process_comm(pid_t pid) {
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log_info("PID"PID_FMT" cmdline: '%s'", pid, c);
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assert_se(get_process_cmdline(pid, 8, false, &d) >= 0);
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log_info("PID"PID_FMT" cmdline truncated: '%s'", pid, d);
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log_info("PID"PID_FMT" cmdline truncated to 8: '%s'", pid, d);
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free(d);
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assert_se(get_process_cmdline(pid, 1, false, &d) >= 0);
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log_info("PID"PID_FMT" cmdline truncated to 1: '%s'", pid, d);
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assert_se(get_process_ppid(pid, &e) >= 0);
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log_info("PID"PID_FMT" PPID: "PID_FMT, pid, e);
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@ -147,6 +155,187 @@ static void test_personality(void) {
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#endif
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}
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static void test_get_process_cmdline_harder(void) {
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char path[] = "/tmp/test-cmdlineXXXXXX";
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_cleanup_close_ int fd = -1;
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_cleanup_free_ char *line = NULL;
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pid_t pid;
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if (geteuid() != 0)
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return;
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pid = fork();
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if (pid > 0) {
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siginfo_t si;
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(void) wait_for_terminate(pid, &si);
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assert_se(si.si_code == CLD_EXITED);
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assert_se(si.si_status == 0);
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return;
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}
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assert_se(pid == 0);
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assert_se(unshare(CLONE_NEWNS) >= 0);
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fd = mkostemp(path, O_CLOEXEC);
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assert_se(fd >= 0);
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assert_se(mount(path, "/proc/self/cmdline", "bind", MS_BIND, NULL) >= 0);
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assert_se(unlink(path) >= 0);
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assert_se(prctl(PR_SET_NAME, "testa") >= 0);
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assert_se(get_process_cmdline(getpid(), 0, false, &line) == -ENOENT);
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assert_se(get_process_cmdline(getpid(), 0, true, &line) >= 0);
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assert_se(streq(line, "[testa]"));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 1, true, &line) >= 0);
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assert_se(streq(line, ""));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 2, true, &line) >= 0);
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assert_se(streq(line, "["));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 3, true, &line) >= 0);
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assert_se(streq(line, "[."));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 4, true, &line) >= 0);
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assert_se(streq(line, "[.."));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 5, true, &line) >= 0);
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assert_se(streq(line, "[..."));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 6, true, &line) >= 0);
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assert_se(streq(line, "[...]"));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 7, true, &line) >= 0);
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assert_se(streq(line, "[t...]"));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 8, true, &line) >= 0);
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assert_se(streq(line, "[testa]"));
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line = mfree(line);
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assert_se(write(fd, "\0\0\0\0\0\0\0\0\0", 10) == 10);
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assert_se(get_process_cmdline(getpid(), 0, false, &line) == -ENOENT);
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assert_se(get_process_cmdline(getpid(), 0, true, &line) >= 0);
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assert_se(streq(line, "[testa]"));
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line = mfree(line);
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assert_se(write(fd, "foo\0bar\0\0\0\0\0", 10) == 10);
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assert_se(get_process_cmdline(getpid(), 0, false, &line) >= 0);
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assert_se(streq(line, "foo bar"));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 0, true, &line) >= 0);
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assert_se(streq(line, "foo bar"));
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line = mfree(line);
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assert_se(write(fd, "quux", 4) == 4);
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assert_se(get_process_cmdline(getpid(), 0, false, &line) >= 0);
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assert_se(streq(line, "foo bar quux"));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 0, true, &line) >= 0);
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assert_se(streq(line, "foo bar quux"));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 1, true, &line) >= 0);
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assert_se(streq(line, ""));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 2, true, &line) >= 0);
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assert_se(streq(line, "."));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 3, true, &line) >= 0);
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assert_se(streq(line, ".."));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 4, true, &line) >= 0);
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assert_se(streq(line, "..."));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 5, true, &line) >= 0);
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assert_se(streq(line, "f..."));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 6, true, &line) >= 0);
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assert_se(streq(line, "fo..."));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 7, true, &line) >= 0);
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assert_se(streq(line, "foo..."));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 8, true, &line) >= 0);
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assert_se(streq(line, "foo..."));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 9, true, &line) >= 0);
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assert_se(streq(line, "foo b..."));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 10, true, &line) >= 0);
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assert_se(streq(line, "foo ba..."));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 11, true, &line) >= 0);
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assert_se(streq(line, "foo bar..."));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 12, true, &line) >= 0);
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assert_se(streq(line, "foo bar..."));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 13, true, &line) >= 0);
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assert_se(streq(line, "foo bar quux"));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 14, true, &line) >= 0);
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assert_se(streq(line, "foo bar quux"));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 1000, true, &line) >= 0);
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assert_se(streq(line, "foo bar quux"));
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line = mfree(line);
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assert_se(ftruncate(fd, 0) >= 0);
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assert_se(prctl(PR_SET_NAME, "aaaa bbbb cccc") >= 0);
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assert_se(get_process_cmdline(getpid(), 0, false, &line) == -ENOENT);
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assert_se(get_process_cmdline(getpid(), 0, true, &line) >= 0);
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assert_se(streq(line, "[aaaa bbbb cccc]"));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 10, true, &line) >= 0);
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assert_se(streq(line, "[aaaa...]"));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 11, true, &line) >= 0);
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assert_se(streq(line, "[aaaa...]"));
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line = mfree(line);
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assert_se(get_process_cmdline(getpid(), 12, true, &line) >= 0);
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assert_se(streq(line, "[aaaa b...]"));
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line = mfree(line);
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safe_close(fd);
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_exit(0);
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}
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int main(int argc, char *argv[]) {
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log_parse_environment();
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log_open();
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@ -164,6 +353,7 @@ int main(int argc, char *argv[]) {
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test_pid_is_unwaited();
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test_pid_is_alive();
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test_personality();
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test_get_process_cmdline_harder();
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return 0;
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}
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