autodata: stash pointers in a binary.

[ccan] / ccan / autodata / autodata.c

diff --git a/ccan/autodata/autodata.c b/ccan/autodata/autodata.c
new file mode 100644 (file)
index 0000000..d8ea88f
--- /dev/null
+++ b/ccan/autodata/autodata.c
@@ -0,0 +1,80 @@
+// Licensed under BSD-MIT: See LICENSE.
+#include "autodata.h"
+#include <stdint.h>
+#include <unistd.h>
+#include <string.h>
+
+#if HAVE_SECTION_START_STOP
+void *autodata_get_section(void *start, void *stop, size_t *nump)
+{
+       *nump = (void **)(stop) - (void **)(start);
+       return start;
+}
+
+void autodata_free(void *table)
+{
+}
+#else
+#include <ccan/ptr_valid/ptr_valid.h>
+
+void *autodata_make_table(const void *example, const char *name, size_t *nump)
+{
+       const char *start, *end, *tag;
+       struct ptr_valid_batch batch;
+       const void *const magic = (void *)AUTODATA_MAGIC;
+       void **table = NULL;
+       char first_magic;
+
+       if (!ptr_valid_batch_start(&batch))
+               return NULL;
+
+       /* Get range to search. */
+       for (start = (char *)((intptr_t)example & ~(getpagesize() - 1));
+            ptr_valid_batch(&batch, start-getpagesize(), 1, sizeof(void *),
+                            false);
+            start -= getpagesize());
+
+       for (end = (char *)((intptr_t)example & ~(getpagesize() - 1));
+            ptr_valid_batch(&batch, end, 1, sizeof(void *), false);
+            end += getpagesize());
+
+       *nump = 0;
+       first_magic = *(char *)&magic;
+       for (tag = memchr(start, first_magic, end - start);
+            tag;
+            tag = memchr(tag+1, first_magic, end - (tag + 1))) {
+               void *adata[4];
+
+               /* We can read 4 void *'s here? */
+               if (tag + sizeof(adata) > end)
+                       continue;
+
+               memcpy(adata, tag, sizeof(adata));
+
+               /* False match? */
+               if (adata[0] != (void *)AUTODATA_MAGIC || adata[1] != tag)
+                       continue;
+
+               /* OK, check name. */
+               if (!ptr_valid_batch_string(&batch, adata[3])
+                   || strcmp(name, adata[3]) != 0)
+                       continue;
+
+               if (!ptr_valid_batch_read(&batch, (char *)adata[2]))
+                       continue;
+
+               table = realloc(table, sizeof(void *) * (*nump + 1));
+               if (!table)
+                       break;
+               table[*nump] = adata[2];
+               (*nump)++;
+       }
+       ptr_valid_batch_end(&batch);
+       return table;
+}
+
+void autodata_free(void *table)
+{
+       free(table);
+}
+#endif