1 files changed, 59 insertions, 0 deletions
diff --git a/elfutils/lib/crc32_file.c b/elfutils/lib/crc32_file.c
new file mode 100644
index 00000000..e6d468b4
--- /dev/null
+++ b/elfutils/lib/crc32_file.c
@@ -0,0 +1,59 @@
+#include "system.h"
+#include <errno.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+
+int
+crc32_file (int fd, uint32_t *resp)
+{
+  unsigned char buffer[1024 * 8];
+  uint32_t crc = 0;
+  off_t off = 0;
+  ssize_t count;
+
+  struct stat st;
+  if (fstat (fd, &st) == 0)
+    {
+      /* Try mapping in the file data.  */
+      size_t mapsize = st.st_size;
+      void *mapped = mmap (NULL, mapsize, PROT_READ, MAP_PRIVATE, fd, 0);
+      if (mapped == MAP_FAILED && errno == ENOMEM)
+	{
+	  const size_t pagesize = sysconf (_SC_PAGE_SIZE);
+	  mapsize = ((mapsize / 2) + pagesize - 1) & -pagesize;
+	  while (mapsize >= pagesize
+		 && (mapped = mmap (NULL, mapsize, PROT_READ, MAP_PRIVATE,
+				    fd, 0)) == MAP_FAILED && errno == ENOMEM)
+	    mapsize /= 2;
+	}
+      if (mapped != MAP_FAILED)
+	{
+	  do
+	    {
+	      if (st.st_size <= (off_t) mapsize)
+		{
+		  *resp = crc32 (crc, mapped, st.st_size);
+		  munmap (mapped, mapsize);
+		  return 0;
+		}
+	      crc = crc32 (crc, mapped, mapsize);
+	      off += mapsize;
+	      st.st_size -= mapsize;
+	    } while (mmap (mapped, mapsize, PROT_READ, MAP_FIXED|MAP_PRIVATE,
+			   fd, off) == mapped);
+	  munmap (mapped, mapsize);
+	}
+    }
+
+  while ((count = TEMP_FAILURE_RETRY (pread (fd, buffer, sizeof buffer,
+					     off))) > 0)
+    {
+      off += count;
+      crc = crc32 (crc, buffer, count);
+    }
+
+  *resp = crc;
+
+  return count == 0 ? 0 : -1;
+}