tools/perf/util/data.c

   1 #include <linux/compiler.h>
   2 #include <linux/kernel.h>
   3 #include <sys/types.h>
   4 #include <sys/stat.h>
   5 #include <unistd.h>
   6 #include <string.h>
   7
   8 #include "data.h"
   9 #include "util.h"
  10 #include "debug.h"
  11
  12 static bool check_pipe(struct perf_data_file *file)
  13 {
  14         struct stat st;
  15         bool is_pipe = false;
  16         int fd = perf_data_file__is_read(file) ?
  17                  STDIN_FILENO : STDOUT_FILENO;
  18
  19         if (!file->path) {
  20                 if (!fstat(fd, &st) && S_ISFIFO(st.st_mode))
  21                         is_pipe = true;
  22         } else {
  23                 if (!strcmp(file->path, "-"))
  24                         is_pipe = true;
  25         }
  26
  27         if (is_pipe)
  28                 file->fd = fd;
  29
  30         return file->is_pipe = is_pipe;
  31 }
  32
  33 static int check_backup(struct perf_data_file *file)
  34 {
  35         struct stat st;
  36
  37         if (!stat(file->path, &st) && st.st_size) {
  38                 /* TODO check errors properly */
  39                 char oldname[PATH_MAX];
  40                 snprintf(oldname, sizeof(oldname), "%s.old",
  41                          file->path);
  42                 unlink(oldname);
  43                 rename(file->path, oldname);
  44         }
  45
  46         return 0;
  47 }
  48
  49 static int open_file_read(struct perf_data_file *file)
  50 {
  51         struct stat st;
  52         int fd;
  53         char sbuf[STRERR_BUFSIZE];
  54
  55         fd = open(file->path, O_RDONLY);
  56         if (fd < 0) {
  57                 int err = errno;
  58
  59                 pr_err("failed to open %s: %s", file->path,
  60                         str_error_r(err, sbuf, sizeof(sbuf)));
  61                 if (err == ENOENT && !strcmp(file->path, "perf.data"))
  62                         pr_err("  (try 'perf record' first)");
  63                 pr_err("\n");
  64                 return -err;
  65         }
  66
  67         if (fstat(fd, &st) < 0)
  68                 goto out_close;
  69
  70         if (!file->force && st.st_uid && (st.st_uid != geteuid())) {
  71                 pr_err("File %s not owned by current user or root (use -f to override)\n",
  72                        file->path);
  73                 goto out_close;
  74         }
  75
  76         if (!st.st_size) {
  77                 pr_info("zero-sized file (%s), nothing to do!\n",
  78                         file->path);
  79                 goto out_close;
  80         }
  81
  82         file->size = st.st_size;
  83         return fd;
  84
  85  out_close:
  86         close(fd);
  87         return -1;
  88 }
  89
  90 static int open_file_write(struct perf_data_file *file)
  91 {
  92         int fd;
  93         char sbuf[STRERR_BUFSIZE];
  94
  95         if (check_backup(file))
  96                 return -1;
  97
  98         fd = open(file->path, O_CREAT|O_RDWR|O_TRUNC, S_IRUSR|S_IWUSR);
  99
 100         if (fd < 0)
 101                 pr_err("failed to open %s : %s\n", file->path,
 102                         str_error_r(errno, sbuf, sizeof(sbuf)));
 103
 104         return fd;
 105 }
 106
 107 static int open_file(struct perf_data_file *file)
 108 {
 109         int fd;
 110
 111         fd = perf_data_file__is_read(file) ?
 112              open_file_read(file) : open_file_write(file);
 113
 114         file->fd = fd;
 115         return fd < 0 ? -1 : 0;
 116 }
 117
 118 int perf_data_file__open(struct perf_data_file *file)
 119 {
 120         if (check_pipe(file))
 121                 return 0;
 122
 123         if (!file->path)
 124                 file->path = "perf.data";
 125
 126         return open_file(file);
 127 }
 128
 129 void perf_data_file__close(struct perf_data_file *file)
 130 {
 131         close(file->fd);
 132 }
 133
 134 ssize_t perf_data_file__write(struct perf_data_file *file,
 135                               void *buf, size_t size)
 136 {
 137         return writen(file->fd, buf, size);
 138 }
 139
 140 int perf_data_file__switch(struct perf_data_file *file,
 141                            const char *postfix,
 142                            size_t pos, bool at_exit)
 143 {
 144         char *new_filepath;
 145         int ret;
 146
 147         if (check_pipe(file))
 148                 return -EINVAL;
 149         if (perf_data_file__is_read(file))
 150                 return -EINVAL;
 151
 152         if (asprintf(&new_filepath, "%s.%s", file->path, postfix) < 0)
 153                 return -ENOMEM;
 154
 155         /*
 156          * Only fire a warning, don't return error, continue fill
 157          * original file.
 158          */
 159         if (rename(file->path, new_filepath))
 160                 pr_warning("Failed to rename %s to %s\n", file->path, new_filepath);
 161
 162         if (!at_exit) {
 163                 close(file->fd);
 164                 ret = perf_data_file__open(file);
 165                 if (ret < 0)
 166                         goto out;
 167
 168                 if (lseek(file->fd, pos, SEEK_SET) == (off_t)-1) {
 169                         ret = -errno;
 170                         pr_debug("Failed to lseek to %zu: %s",
 171                                  pos, strerror(errno));
 172                         goto out;
 173                 }
 174         }
 175         ret = file->fd;
 176 out:
 177         free(new_filepath);
 178         return ret;
 179 }