Re: [PATCH v3 03/27] util/hexdump: Use a GString for qemu_hexdump_line

[Richard Henderson]

On 4/12/24 10:41, Philippe Mathieu-Daudé wrote:

-void qemu_hexdump_line(char *line, const void *bufptr, size_t len)
+GString *qemu_hexdump_line(GString *str, const void *vbuf, size_t len)
  {
-    const char *buf = bufptr;
-    int i, c;
+    const uint8_t *buf = vbuf;
+    size_t i;
-    if (len > QEMU_HEXDUMP_LINE_BYTES) {
-        len = QEMU_HEXDUMP_LINE_BYTES;
+    if (str == NULL) {
+        /* Estimate the length of the output to avoid reallocs. */
+        i = len * 3 + len / 4;
+        str = g_string_sized_new(i + 1);
      }

[*]
          else {
            g_string_truncate(str, 0);
          }

...

@@ -49,24 +52,26 @@ static void asciidump_line(char *line, const void *bufptr, 
size_t len)
      *line = '\0';
  }
+#define QEMU_HEXDUMP_LINE_BYTES 16
  #define QEMU_HEXDUMP_LINE_WIDTH \
      (QEMU_HEXDUMP_LINE_BYTES * 2 + QEMU_HEXDUMP_LINE_BYTES / 4)
  void qemu_hexdump(FILE *fp, const char *prefix,
                    const void *bufptr, size_t size)
  {
-    char line[QEMU_HEXDUMP_LINE_LEN];
+    g_autoptr(GString) str = g_string_sized_new(QEMU_HEXDUMP_LINE_WIDTH + 1);
      char ascii[QEMU_HEXDUMP_LINE_BYTES + 1];
      size_t b, len;
      for (b = 0; b < size; b += len) {
          len = MIN(size - b, QEMU_HEXDUMP_LINE_BYTES);
-        qemu_hexdump_line(line, bufptr + b, len);
+        g_string_truncate(str, 0);

Shouldn't we truncate in [*] ?

The usage in tpm puts several lines together in one string,
adding \n in between, for output in one go.


r~