Fix fread() with 2gb+ sizes

libc/stdio/fread_unlocked.c

@@ -16,6 +16,7 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/assert.h"
 #include "libc/calls/calls.h"
 #include "libc/calls/struct/iovec.h"
 #include "libc/errno.h"
@@ -25,6 +26,41 @@
 #include "libc/stdio/stdio.h"
 #include "libc/str/str.h"
 #include "libc/sysv/consts/o.h"
+#include "libc/sysv/errfuns.h"
+
+static ssize_t readvall(int fd, struct iovec *iov, int iovlen) {
+  int olde;
+  ssize_t rc;
+  size_t got, toto;
+  toto = 0;
+  olde = errno;
+  do {
+    if ((rc = readv(fd, iov, iovlen)) == -1) {
+      if (toto && errno == EINTR) {
+        errno = olde;
+        continue;
+      }
+      return -1;
+    }
+    got = rc;
+    toto += got;
+    for (;;) {
+      if (!iov->iov_len) {
+        --iovlen;
+        ++iov;
+      } else if (got >= iov->iov_len) {
+        got -= iov->iov_len;
+        --iovlen;
+        ++iov;
+      } else {
+        iov->iov_base += got;
+        iov->iov_len -= got;
+        break;
+      }
+    }
+  } while (got && iovlen);
+  return toto;
+}
 
 /**
  * Reads data from stream.
@@ -36,11 +72,10 @@
 size_t fread_unlocked(void *buf, size_t stride, size_t count, FILE *f) {
   char *p;
   ssize_t rc;
-  size_t n, m;
   struct iovec iov[2];
-  if (!stride) {
-    return 0;
-  }
+  size_t n, m, got, need;
+
+  // check state and parameters
   if ((f->iomode & O_ACCMODE) == O_WRONLY) {
     f->state = errno = EBADF;
     return 0;
@@ -53,52 +88,74 @@ size_t fread_unlocked(void *buf, size_t stride, size_t count, FILE *f) {
     f->state = errno = EOVERFLOW;
     return 0;
   }
+  if (!n)
+    return 0;
+
+  // try to fulfill request from buffer if possible
   p = buf;
   m = f->end - f->beg;
-  if (MIN(n, m)) {
-    memcpy(p, f->buf + f->beg, MIN(n, m));
-  }
-  if (n < m) {
-    f->beg += n;
-    return count;
-  }
-  if (n == m) {
-    f->beg = f->end = 0;
+  if (n <= m) {
+    memcpy(p, f->buf + f->beg, n);
+    if ((f->beg += n) == f->end) {
+      f->beg = 0;
+      f->end = 0;
+    }
     return count;
   }
+
+  // handle end-of-file condition in fileless mode
   if (f->fd == -1) {
-    f->beg = 0;
-    f->end = 0;
-    f->state = -1;
+    m /= stride;
+    m *= stride;
+    if (m)
+      memcpy(p, f->buf + f->beg, m);
+    if ((f->beg += m) == f->end) {
+      f->state = EOF;
+      f->beg = 0;
+      f->end = 0;
+    }
     return m / stride;
   }
+
+  // `n` is number of bytes requested by caller
+  // `m` is how much of `n` came from existing buffer
+  // `iov[0]` reads remainder of the caller request
+  // `iov[1]` reads ahead extra content into buffer
+  if (m)
+    memcpy(p, f->buf + f->beg, m);
   iov[0].iov_base = p + m;
-  iov[0].iov_len = n - m;
+  iov[0].iov_len = need = n - m;
   if (f->bufmode != _IONBF && n < f->size) {
     iov[1].iov_base = f->buf;
-    if (f->size > PUSHBACK) {
+    if (f->size > PUSHBACK)
       iov[1].iov_len = f->size - PUSHBACK;
-    } else {
+    else
       iov[1].iov_len = f->size;
-    }
   } else {
     iov[1].iov_base = NULL;
     iov[1].iov_len = 0;
   }
-  if ((rc = readv(f->fd, iov, 2)) == -1) {
+  if ((rc = readvall(f->fd, iov, 2)) == -1) {
     f->state = errno;
     return 0;
   }
-  n = rc;
-  f->beg = 0;
-  f->end = 0;
-  if (n > iov[0].iov_len) {
-    f->end += n - iov[0].iov_len;
-    return count;
-  } else {
-    n = (m + n) / stride;
-    if (n < count)
-      f->state = -1;
-    return n;
+  got = rc;
+
+  // handle partial fulfillment
+  if (got < need) {
+    got += m;
+    if (got % stride) {
+      f->state = eio();
+      return 0;
+    }
+    f->beg = 0;
+    f->end = 0;
+    f->state = EOF;
+    return got / stride;
   }
+
+  // handle overfulfillment
+  f->beg = 0;
+  f->end = got - need;
+  return count;
 }

libc/stdio/fwrite_unlocked.c

@@ -27,6 +27,40 @@
 #include "libc/str/str.h"
 #include "libc/sysv/consts/o.h"
 
+static ssize_t writevall(int fd, struct iovec *iov, int iovlen) {
+  int olde;
+  ssize_t rc;
+  size_t got, toto;
+  toto = 0;
+  olde = errno;
+  do {
+    if ((rc = writev(fd, iov, iovlen)) == -1) {
+      if (toto && errno == EINTR) {
+        errno = olde;
+        continue;
+      }
+      return -1;
+    }
+    got = rc;
+    toto += got;
+    for (;;) {
+      if (!iov->iov_len) {
+        --iovlen;
+        ++iov;
+      } else if (got >= iov->iov_len) {
+        got -= iov->iov_len;
+        --iovlen;
+        ++iov;
+      } else {
+        iov->iov_base += got;
+        iov->iov_len -= got;
+        break;
+      }
+    }
+  } while (got && iovlen);
+  return toto;
+}
+
 /**
  * Writes data to stream.
  *
@@ -104,7 +138,7 @@ size_t fwrite_unlocked(const void *data, size_t stride, size_t count, FILE *f) {
   iov[1].iov_base = (void *)data;
   iov[1].iov_len = n;
   n += f->beg;
-  if (__robust_writev(f->fd, iov, 2) == -1) {
+  if ((rc = writevall(f->fd, iov, 2)) == -1) {
     f->state = errno;
     return 0;
   }

libc/stdio/vdprintf.c

@@ -16,7 +16,7 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
-#include "libc/calls/struct/iovec.internal.h"
+#include "libc/calls/struct/iovec.h"
 #include "libc/dce.h"
 #include "libc/fmt/internal.h"
 #include "libc/limits.h"
@@ -42,7 +42,7 @@ static int vdprintf_putc(const char *s, struct VdprintfState *t, size_t n) {
       iov[0].iov_len = t->n;
       iov[1].iov_base = (void *)s;
       iov[1].iov_len = n;
-      if (__robust_writev(t->fd, iov, 2) == -1) {
+      if (writev(t->fd, iov, 2) == -1) {
         return -1;
       }
       t->t += t->n;
@@ -68,7 +68,7 @@ int vdprintf(int fd, const char *fmt, va_list va) {
   if (t.n) {
     iov[0].iov_base = t.b;
     iov[0].iov_len = t.n;
-    if (__robust_writev(t.fd, iov, 1) == -1) {
+    if (writev(t.fd, iov, 1) == -1) {
       return -1;
     }
     t.t += t.n;