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
  11 static bool check_pipe(struct perf_data_file *file)
  12 {
  13         struct stat st;
  14         bool is_pipe = false;
  15         int fd = perf_data_file__is_read(file) ?
  16                  STDIN_FILENO : STDOUT_FILENO;
  17
  18         if (!file->path) {
  19                 if (!fstat(fd, &st) && S_ISFIFO(st.st_mode))
  20                         is_pipe = true;
  21         } else {
  22                 if (!strcmp(file->path, "-"))
  23                         is_pipe = true;
  24         }
  25
  26         if (is_pipe)
  27                 file->fd = fd;
  28
  29         return file->is_pipe = is_pipe;
  30 }
  31
  32 static int check_backup(struct perf_data_file *file)
  33 {
  34         struct stat st;
  35
  36         if (!stat(file->path, &st) && st.st_size) {
  37                 /* TODO check errors properly */
  38                 char oldname[PATH_MAX];
  39                 snprintf(oldname, sizeof(oldname), "%s.old",
  40                          file->path);
  41                 unlink(oldname);
  42                 rename(file->path, oldname);
  43         }
  44
  45         return 0;
  46 }
  47
  48 static int open_file_read(struct perf_data_file *file)
  49 {
  50         struct stat st;
  51         int fd;
  52
  53         fd = open(file->path, O_RDONLY);
  54         if (fd < 0) {
  55                 int err = errno;
  56
  57                 pr_err("failed to open %s: %s", file->path, strerror(err));
  58                 if (err == ENOENT && !strcmp(file->path, "perf.data"))
  59                         pr_err("  (try 'perf record' first)");
  60                 pr_err("\n");
  61                 return -err;
  62         }
  63
  64         if (fstat(fd, &st) < 0)
  65                 goto out_close;
  66
  67         if (!file->force && st.st_uid && (st.st_uid != geteuid())) {
  68                 pr_err("file %s not owned by current user or root\n",
  69                        file->path);
  70                 goto out_close;
  71         }
  72
  73         if (!st.st_size) {
  74                 pr_info("zero-sized file (%s), nothing to do!\n",
  75                         file->path);
  76                 goto out_close;
  77         }
  78
  79         file->size = st.st_size;
  80         return fd;
  81
  82  out_close:
  83         close(fd);
  84         return -1;
  85 }
  86
  87 static int open_file_write(struct perf_data_file *file)
  88 {
  89         if (check_backup(file))
  90                 return -1;
  91
  92         return open(file->path, O_CREAT|O_RDWR|O_TRUNC, S_IRUSR|S_IWUSR);
  93 }
  94
  95 static int open_file(struct perf_data_file *file)
  96 {
  97         int fd;
  98
  99         fd = perf_data_file__is_read(file) ?
 100              open_file_read(file) : open_file_write(file);
 101
 102         file->fd = fd;
 103         return fd < 0 ? -1 : 0;
 104 }
 105
 106 int perf_data_file__open(struct perf_data_file *file)
 107 {
 108         if (check_pipe(file))
 109                 return 0;
 110
 111         if (!file->path)
 112                 file->path = "perf.data";
 113
 114         return open_file(file);
 115 }
 116
 117 void perf_data_file__close(struct perf_data_file *file)
 118 {
 119         close(file->fd);
 120 }
 121
 122 ssize_t perf_data_file__write(struct perf_data_file *file,
 123                               void *buf, size_t size)
 124 {
 125         return writen(file->fd, buf, size);
 126 }