Fix fread() with 2gb+ sizes

test/posix/fread3gb_test.c

@@ -0,0 +1,73 @@
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#define SIZE ((size_t)2 * 1024 * 1024 * 1024 + 13)
+
+char path[PATH_MAX];
+
+void teardown(void) {
+  unlink(path);
+}
+
+int setup(void) {
+  int fd;
+  struct stat st;
+  const char *tmpdir;
+  if (!stat("/dev/shm", &st))
+    strlcpy(path, "/dev/shm", sizeof(path));
+  else if ((tmpdir = getenv("TMPDIR")))
+    strlcpy(path, tmpdir, sizeof(path));
+  else
+    strlcpy(path, "/tmp", sizeof(path));
+  strlcat(path, "/fread3gb.XXXXXX", sizeof(path));
+  if ((fd = mkstemp(path)) == -1)
+    return 1;
+  if (ftruncate(fd, SIZE))
+    return 2;
+  if (pwrite(fd, "a", 1, 0) != 1)
+    return 3;
+  if (pwrite(fd, "z", 1, SIZE - 1) != 1)
+    return 4;
+  if (close(fd))
+    return 5;
+  return 0;
+}
+
+int test(void) {
+  FILE *f;
+  char *buf;
+  size_t rc;
+  if (!(f = fopen(path, "r")))
+    return 6;
+  if (!(buf = malloc(SIZE)))
+    return 7;
+  if ((rc = fread(buf, SIZE, 1, f)) != 1) {
+    fprintf(stderr, "tell = %zu\n", ftello(f));
+    fprintf(stderr, "rc = %zu\n", rc);
+    perror("fread");
+    return 8;
+  }
+  if (buf[0] != 'a')
+    return 9;
+  if (buf[SIZE - 1] != 'z')
+    return 10;
+  if (fclose(f))
+    return 11;
+  return 0;
+}
+
+int main(int argc, char *argv[]) {
+  int rc;
+  if ((rc = setup())) {
+    perror(path);
+    teardown();
+    return rc;
+  }
+  rc = test();
+  teardown();
+  return rc;
+}