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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 | // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) /* Copyright (c) 2015-2017 Daniel Borkmann */ /* Copyright (c) 2018 Netronome Systems, Inc. */ #include <errno.h> #include <limits.h> #include <signal.h> #include <stdio.h> #include <string.h> #include <unistd.h> #include <linux/magic.h> #include <fcntl.h> #include <sys/vfs.h> #include "main.h" #ifndef TRACEFS_MAGIC # define TRACEFS_MAGIC 0x74726163 #endif #define _textify(x) #x #define textify(x) _textify(x) FILE *trace_pipe_fd; char *buff; static int validate_tracefs_mnt(const char *mnt, unsigned long magic) { struct statfs st_fs; if (statfs(mnt, &st_fs) < 0) return -ENOENT; if ((unsigned long)st_fs.f_type != magic) return -ENOENT; return 0; } static bool find_tracefs_mnt_single(unsigned long magic, char *mnt, const char *mntpt) { size_t src_len; if (validate_tracefs_mnt(mntpt, magic)) return false; src_len = strlen(mntpt); if (src_len + 1 >= PATH_MAX) { p_err("tracefs mount point name too long"); return false; } strcpy(mnt, mntpt); return true; } static bool get_tracefs_pipe(char *mnt) { static const char * const known_mnts[] = { "/sys/kernel/debug/tracing", "/sys/kernel/tracing", "/tracing", "/trace", }; const char *pipe_name = "/trace_pipe"; const char *fstype = "tracefs"; char type[100], format[32]; const char * const *ptr; bool found = false; FILE *fp; for (ptr = known_mnts; ptr < known_mnts + ARRAY_SIZE(known_mnts); ptr++) if (find_tracefs_mnt_single(TRACEFS_MAGIC, mnt, *ptr)) goto exit_found; fp = fopen("/proc/mounts", "r"); if (!fp) return false; /* Allow room for NULL terminating byte and pipe file name */ snprintf(format, sizeof(format), "%%*s %%%zds %%99s %%*s %%*d %%*d\\n", PATH_MAX - strlen(pipe_name) - 1); while (fscanf(fp, format, mnt, type) == 2) if (strcmp(type, fstype) == 0) { found = true; break; } fclose(fp); /* The string from fscanf() might be truncated, check mnt is valid */ if (found && validate_tracefs_mnt(mnt, TRACEFS_MAGIC)) goto exit_found; if (block_mount) return false; p_info("could not find tracefs, attempting to mount it now"); /* Most of the time, tracefs is automatically mounted by debugfs at * /sys/kernel/debug/tracing when we try to access it. If we could not * find it, it is likely that debugfs is not mounted. Let's give one * attempt at mounting just tracefs at /sys/kernel/tracing. */ strcpy(mnt, known_mnts[1]); if (mount_tracefs(mnt)) return false; exit_found: strcat(mnt, pipe_name); return true; } static void exit_tracelog(int signum) { fclose(trace_pipe_fd); free(buff); if (json_output) { jsonw_end_array(json_wtr); jsonw_destroy(&json_wtr); } exit(0); } int do_tracelog(int argc, char **argv) { const struct sigaction act = { .sa_handler = exit_tracelog }; char trace_pipe[PATH_MAX]; size_t buff_len = 0; if (json_output) jsonw_start_array(json_wtr); if (!get_tracefs_pipe(trace_pipe)) return -1; trace_pipe_fd = fopen(trace_pipe, "r"); if (!trace_pipe_fd) { p_err("could not open trace pipe: %s", strerror(errno)); return -1; } sigaction(SIGHUP, &act, NULL); sigaction(SIGINT, &act, NULL); sigaction(SIGTERM, &act, NULL); while (1) { ssize_t ret; ret = getline(&buff, &buff_len, trace_pipe_fd); if (ret <= 0) { p_err("failed to read content from trace pipe: %s", strerror(errno)); break; } if (json_output) jsonw_string(json_wtr, buff); else printf("%s", buff); } fclose(trace_pipe_fd); free(buff); return -1; } |