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Diffstat (limited to '')
| -rw-r--r-- | lib/common/procfs.c | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/lib/common/procfs.c b/lib/common/procfs.c new file mode 100644 index 0000000..8179cc9 --- /dev/null +++ b/lib/common/procfs.c @@ -0,0 +1,227 @@ +/* + * Copyright 2015-2022 the Pacemaker project contributors + * + * The version control history for this file may have further details. + * + * This source code is licensed under the GNU Lesser General Public License + * version 2.1 or later (LGPLv2.1+) WITHOUT ANY WARRANTY. + */ + +#include <crm_internal.h> + +#ifndef _GNU_SOURCE +# define _GNU_SOURCE +#endif + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/stat.h> +#include <sys/types.h> +#include <dirent.h> +#include <ctype.h> + +/*! + * \internal + * \brief Get process ID and name associated with a /proc directory entry + * + * \param[in] entry Directory entry (must be result of readdir() on /proc) + * \param[out] name If not NULL, a char[16] to hold the process name + * \param[out] pid If not NULL, will be set to process ID of entry + * + * \return Standard Pacemaker return code + * \note This should be called only on Linux systems, as not all systems that + * support /proc store process names and IDs in the same way. The kernel + * limits the process name to the first 15 characters (plus terminator). + * It would be nice if there were a public kernel API constant for that + * limit, but there isn't. + */ +static int +pcmk__procfs_process_info(const struct dirent *entry, char *name, pid_t *pid) +{ + int fd, local_pid; + FILE *file; + struct stat statbuf; + char procpath[128] = { 0 }; + + /* We're only interested in entries whose name is a PID, + * so skip anything non-numeric or that is too long. + * + * 114 = 128 - strlen("/proc/") - strlen("/status") - 1 + */ + local_pid = atoi(entry->d_name); + if ((local_pid <= 0) || (strlen(entry->d_name) > 114)) { + return -1; + } + if (pid) { + *pid = (pid_t) local_pid; + } + + /* Get this entry's file information */ + strcpy(procpath, "/proc/"); + strcat(procpath, entry->d_name); + fd = open(procpath, O_RDONLY); + if (fd < 0 ) { + return -1; + } + if (fstat(fd, &statbuf) < 0) { + close(fd); + return -1; + } + close(fd); + + /* We're only interested in subdirectories */ + if (!S_ISDIR(statbuf.st_mode)) { + return -1; + } + + /* Read the first entry ("Name:") from the process's status file. + * We could handle the valgrind case if we parsed the cmdline file + * instead, but that's more of a pain than it's worth. + */ + if (name != NULL) { + strcat(procpath, "/status"); + file = fopen(procpath, "r"); + if (!file) { + return -1; + } + if (fscanf(file, "Name:\t%15[^\n]", name) != 1) { + fclose(file); + return -1; + } + name[15] = 0; + fclose(file); + } + + return 0; +} + +/*! + * \internal + * \brief Return process ID of a named process + * + * \param[in] name Process name (as used in /proc/.../status) + * + * \return Process ID of named process if running, 0 otherwise + * + * \note This will return 0 if the process is being run via valgrind. + * This should be called only on Linux systems. + */ +pid_t +pcmk__procfs_pid_of(const char *name) +{ + DIR *dp; + struct dirent *entry; + pid_t pid = 0; + char entry_name[64] = { 0 }; + + dp = opendir("/proc"); + if (dp == NULL) { + crm_notice("Can not read /proc directory to track existing components"); + return 0; + } + + while ((entry = readdir(dp)) != NULL) { + if ((pcmk__procfs_process_info(entry, entry_name, &pid) == pcmk_rc_ok) + && pcmk__str_eq(entry_name, name, pcmk__str_casei) + && (pcmk__pid_active(pid, NULL) == pcmk_rc_ok)) { + + crm_info("Found %s active as process %lld", name, (long long) pid); + break; + } + pid = 0; + } + closedir(dp); + return pid; +} + +/*! + * \internal + * \brief Calculate number of logical CPU cores from procfs + * + * \return Number of cores (or 1 if unable to determine) + */ +unsigned int +pcmk__procfs_num_cores(void) +{ + int cores = 0; + FILE *stream = NULL; + + /* Parse /proc/stat instead of /proc/cpuinfo because it's smaller */ + stream = fopen("/proc/stat", "r"); + if (stream == NULL) { + crm_perror(LOG_INFO, "Could not open /proc/stat"); + } else { + char buffer[2048]; + + while (fgets(buffer, sizeof(buffer), stream)) { + if (pcmk__starts_with(buffer, "cpu") && isdigit(buffer[3])) { + ++cores; + } + } + fclose(stream); + } + return cores? cores : 1; +} + +/*! + * \internal + * \brief Get the executable path corresponding to a process ID + * + * \param[in] pid Process ID to check + * \param[out] path Where to store executable path + * \param[in] path_size Size of \p path in characters (ideally PATH_MAX) + * + * \return Standard Pacemaker error code (as possible errno values from + * readlink()) + */ +int +pcmk__procfs_pid2path(pid_t pid, char path[], size_t path_size) +{ +#if HAVE_LINUX_PROCFS + char procfs_exe_path[PATH_MAX]; + ssize_t link_rc; + + if (snprintf(procfs_exe_path, PATH_MAX, "/proc/%lld/exe", + (long long) pid) >= PATH_MAX) { + return ENAMETOOLONG; // Truncated (shouldn't be possible in practice) + } + + link_rc = readlink(procfs_exe_path, path, path_size - 1); + if (link_rc < 0) { + return errno; + } else if (link_rc >= (path_size - 1)) { + return ENAMETOOLONG; + } + + path[link_rc] = '\0'; + return pcmk_rc_ok; +#else + return EOPNOTSUPP; +#endif // HAVE_LINUX_PROCFS +} + +/*! + * \internal + * \brief Check whether process ID information is available from procfs + * + * \return true if process ID information is available, otherwise false + */ +bool +pcmk__procfs_has_pids(void) +{ +#if HAVE_LINUX_PROCFS + static bool have_pids = false; + static bool checked = false; + + if (!checked) { + char path[PATH_MAX]; + + have_pids = pcmk__procfs_pid2path(getpid(), path, sizeof(path)) == pcmk_rc_ok; + checked = true; + } + return have_pids; +#else + return false; +#endif // HAVE_LINUX_PROCFS +} |