tools/perf/util/strbuf.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include "debug.h"
   3 #include "util.h"
   4 #include <linux/kernel.h>
   5 #include <errno.h>
   6
   7 /*
   8  * Used as the default ->buf value, so that people can always assume
   9  * buf is non NULL and ->buf is NUL terminated even for a freshly
  10  * initialized strbuf.
  11  */
  12 char strbuf_slopbuf[1];
  13
  14 int strbuf_init(struct strbuf *sb, ssize_t hint)
  15 {
  16         sb->alloc = sb->len = 0;
  17         sb->buf = strbuf_slopbuf;
  18         if (hint)
  19                 return strbuf_grow(sb, hint);
  20         return 0;
  21 }
  22
  23 void strbuf_release(struct strbuf *sb)
  24 {
  25         if (sb->alloc) {
  26                 zfree(&sb->buf);
  27                 strbuf_init(sb, 0);
  28         }
  29 }
  30
  31 char *strbuf_detach(struct strbuf *sb, size_t *sz)
  32 {
  33         char *res = sb->alloc ? sb->buf : NULL;
  34         if (sz)
  35                 *sz = sb->len;
  36         strbuf_init(sb, 0);
  37         return res;
  38 }
  39
  40 int strbuf_grow(struct strbuf *sb, size_t extra)
  41 {
  42         char *buf;
  43         size_t nr = sb->len + extra + 1;
  44
  45         if (nr < sb->alloc)
  46                 return 0;
  47
  48         if (nr <= sb->len)
  49                 return -E2BIG;
  50
  51         if (alloc_nr(sb->alloc) > nr)
  52                 nr = alloc_nr(sb->alloc);
  53
  54         /*
  55          * Note that sb->buf == strbuf_slopbuf if sb->alloc == 0, and it is
  56          * a static variable. Thus we have to avoid passing it to realloc.
  57          */
  58         buf = realloc(sb->alloc ? sb->buf : NULL, nr * sizeof(*buf));
  59         if (!buf)
  60                 return -ENOMEM;
  61
  62         sb->buf = buf;
  63         sb->alloc = nr;
  64         return 0;
  65 }
  66
  67 int strbuf_addch(struct strbuf *sb, int c)
  68 {
  69         int ret = strbuf_grow(sb, 1);
  70         if (ret)
  71                 return ret;
  72
  73         sb->buf[sb->len++] = c;
  74         sb->buf[sb->len] = '\0';
  75         return 0;
  76 }
  77
  78 int strbuf_add(struct strbuf *sb, const void *data, size_t len)
  79 {
  80         int ret = strbuf_grow(sb, len);
  81         if (ret)
  82                 return ret;
  83
  84         memcpy(sb->buf + sb->len, data, len);
  85         return strbuf_setlen(sb, sb->len + len);
  86 }
  87
  88 static int strbuf_addv(struct strbuf *sb, const char *fmt, va_list ap)
  89 {
  90         int len, ret;
  91         va_list ap_saved;
  92
  93         if (!strbuf_avail(sb)) {
  94                 ret = strbuf_grow(sb, 64);
  95                 if (ret)
  96                         return ret;
  97         }
  98
  99         va_copy(ap_saved, ap);
 100         len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap);
 101         if (len < 0) {
 102                 va_end(ap_saved);
 103                 return len;
 104         }
 105         if (len > strbuf_avail(sb)) {
 106                 ret = strbuf_grow(sb, len);
 107                 if (ret) {
 108                         va_end(ap_saved);
 109                         return ret;
 110                 }
 111                 len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap_saved);
 112                 va_end(ap_saved);
 113                 if (len > strbuf_avail(sb)) {
 114                         pr_debug("this should not happen, your vsnprintf is broken");
 115                         va_end(ap_saved);
 116                         return -EINVAL;
 117                 }
 118         }
 119         va_end(ap_saved);
 120         return strbuf_setlen(sb, sb->len + len);
 121 }
 122
 123 int strbuf_addf(struct strbuf *sb, const char *fmt, ...)
 124 {
 125         va_list ap;
 126         int ret;
 127
 128         va_start(ap, fmt);
 129         ret = strbuf_addv(sb, fmt, ap);
 130         va_end(ap);
 131         return ret;
 132 }
 133
 134 ssize_t strbuf_read(struct strbuf *sb, int fd, ssize_t hint)
 135 {
 136         size_t oldlen = sb->len;
 137         size_t oldalloc = sb->alloc;
 138         int ret;
 139
 140         ret = strbuf_grow(sb, hint ? hint : 8192);
 141         if (ret)
 142                 return ret;
 143
 144         for (;;) {
 145                 ssize_t cnt;
 146
 147                 cnt = read(fd, sb->buf + sb->len, sb->alloc - sb->len - 1);
 148                 if (cnt < 0) {
 149                         if (oldalloc == 0)
 150                                 strbuf_release(sb);
 151                         else
 152                                 strbuf_setlen(sb, oldlen);
 153                         return cnt;
 154                 }
 155                 if (!cnt)
 156                         break;
 157                 sb->len += cnt;
 158                 ret = strbuf_grow(sb, 8192);
 159                 if (ret)
 160                         return ret;
 161         }
 162
 163         sb->buf[sb->len] = '\0';
 164         return sb->len - oldlen;
 165 }