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bcc_perf_map.c
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bcc_perf_map.c
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/*
* Copyright (c) 2016 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <ctype.h>
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "bcc_perf_map.h"
bool bcc_is_perf_map(const char *path) {
char* pos = strstr(path, ".map");
// Path ends with ".map"
return (pos != NULL) && (*(pos + 4)== 0);
}
bool bcc_is_valid_perf_map(const char *path) {
return bcc_is_perf_map(path) && (access(path, R_OK) == 0);
}
int bcc_perf_map_nstgid(int pid) {
char status_path[64];
FILE *status;
snprintf(status_path, sizeof(status_path), "/proc/%d/status", pid);
status = fopen(status_path, "r");
if (!status)
return -1;
// return the original PID if we fail to work out the TGID
int nstgid = pid;
size_t size = 0;
char *line = NULL;
while (getline(&line, &size, status) != -1) {
// check Tgid line first in case CONFIG_PID_NS is off
if (strstr(line, "Tgid:") != NULL)
nstgid = (int)strtol(strrchr(line, '\t'), NULL, 10);
if (strstr(line, "NStgid:") != NULL)
// PID namespaces can be nested -- last number is innermost PID
nstgid = (int)strtol(strrchr(line, '\t'), NULL, 10);
}
free(line);
fclose(status);
return nstgid;
}
bool bcc_perf_map_path(char *map_path, size_t map_len, int pid) {
char source[64];
snprintf(source, sizeof(source), "/proc/%d/root", pid);
char target[4096];
ssize_t target_len = readlink(source, target, sizeof(target) - 1);
if (target_len == -1)
return false;
target[target_len] = '\0';
if (strcmp(target, "/") == 0)
target[0] = '\0';
int nstgid = bcc_perf_map_nstgid(pid);
snprintf(map_path, map_len, "%s/tmp/perf-%d.map", target, nstgid);
return true;
}
int bcc_perf_map_foreach_sym(const char *path, bcc_perf_map_symcb callback,
void* payload) {
FILE* file = fopen(path, "r");
if (!file)
return -1;
char *line = NULL;
size_t size = 0;
long long begin, len;
while (getline(&line, &size, file) != -1) {
char *cursor = line;
char *newline, *sep;
begin = strtoull(cursor, &sep, 16);
if (begin == 0 || *sep != ' ' || (begin == ULLONG_MAX && errno == ERANGE))
continue;
cursor = sep;
while (*cursor && isspace(*cursor)) cursor++;
len = strtoull(cursor, &sep, 16);
if (*sep != ' ' ||
(sep == cursor && len == 0) ||
(len == ULLONG_MAX && errno == ERANGE))
continue;
cursor = sep;
while (*cursor && isspace(*cursor)) cursor++;
newline = strchr(cursor, '\n');
if (newline)
newline[0] = '\0';
callback(cursor, begin, len, payload);
}
free(line);
fclose(file);
return 0;
}