radv/gfx10: implement a bug workaround for NGG -> legacy transitions

[mesa.git] / src / util / os_file.c

diff --git a/src/util/os_file.c b/src/util/os_file.c
index ee34a75a2e0d08de96eb757ed269564e1eb339a2..ae41506332d3863e77b64669b619aa551b386d3e 100644 (file)
--- a/src/util/os_file.c
+++ b/src/util/os_file.c
@@ -6,7 +6,30 @@
 #include "os_file.h"
 
 #include <errno.h>
+#include <fcntl.h>
 #include <stdlib.h>
+#include <sys/stat.h>
+
+
+#if defined(WIN32)
+#include <io.h>
+#define open _open
+#define fdopen _fdopen
+#define O_CREAT _O_CREAT
+#define O_EXCL _O_EXCL
+#define O_WRONLY _O_WRONLY
+#endif
+
+
+FILE *
+os_file_create_unique(const char *filename, int filemode)
+{
+   int fd = open(filename, O_CREAT | O_EXCL | O_WRONLY, filemode);
+   if (fd == -1)
+      return NULL;
+   return fdopen(fd, "w");
+}
+
 
 #if defined(__linux__)
 
@@ -29,20 +52,40 @@ readN(int fd, char *buf, size_t len)
       if (ret == -EINTR || ret == -EAGAIN)
          continue;
 
-      if (ret <= 0)
+      if (ret <= 0) {
+         err = ret;
          break;
+      }
 
       total += ret;
    } while (total != len);
 
-   return total ? total : err;
+   return total ? (ssize_t)total : err;
 }
 
-static char *
-read_grow(int fd)
+char *
+os_read_file(const char *filename)
 {
+   /* Note that this also serves as a slight margin to avoid a 2x grow when
+    * the file is just a few bytes larger when we read it than when we
+    * fstat'ed it.
+    * The string's NULL terminator is also included in here.
+    */
    size_t len = 64;
 
+   int fd = open(filename, O_RDONLY);
+   if (fd == -1) {
+      /* errno set by open() */
+      return NULL;
+   }
+
+   /* Pre-allocate a buffer at least the size of the file if we can read
+    * that information.
+    */
+   struct stat stat;
+   if (fstat(fd, &stat) == 0)
+      len += stat.st_size;
+
    char *buf = malloc(len);
    if (!buf) {
       close(fd);
@@ -50,9 +93,9 @@ read_grow(int fd)
       return NULL;
    }
 
-   ssize_t read;
+   ssize_t actually_read;
    size_t offset = 0, remaining = len - 1;
-   while ((read = readN(fd, buf + offset, remaining)) == remaining) {
+   while ((actually_read = readN(fd, buf + offset, remaining)) == (ssize_t)remaining) {
       char *newbuf = realloc(buf, 2 * len);
       if (!newbuf) {
          free(buf);
@@ -63,56 +106,27 @@ read_grow(int fd)
 
       buf = newbuf;
       len *= 2;
-      offset += read;
+      offset += actually_read;
       remaining = len - offset - 1;
    }
 
    close(fd);
 
-   if (read > 0)
-      offset += read;
+   if (actually_read > 0)
+      offset += actually_read;
 
-   buf[offset] = '\0';
-
-   return buf;
-}
-
-char *
-os_read_file(const char *filename)
-{
-   size_t len = 0;
-
-   int fd = open(filename, O_RDONLY);
-   if (fd == -1) {
-      /* errno set by open() */
-      return NULL;
-   }
-
-   struct stat stat;
-   if (fstat(fd, &stat) == 0)
-      len = stat.st_size;
-
-   if (!len)
-      return read_grow(fd);
-
-   /* add NULL terminator */
-   len++;
-
-   char *buf = malloc(len);
-   if (!buf) {
+   /* Final resize to actual size */
+   len = offset + 1;
+   char *newbuf = realloc(buf, len);
+   if (!newbuf) {
+      free(buf);
       close(fd);
       errno = -ENOMEM;
       return NULL;
    }
+   buf = newbuf;
 
-   ssize_t read = readN(fd, buf, len - 1);
-
-   close(fd);
-
-   if (read == -1)
-      return NULL;
-
-   buf[read] = '\0';
+   buf[offset] = '\0';
 
    return buf;
 }