[PATCH v4] hw/core/loader: allow loading larger ROMs

[Gregor Haas <gregorhaas1997@gmail.com>]

The read() syscall is not guaranteed to return all data from a file. The
default ROM loader implementation currently does not take this into account,
instead failing if all bytes are not read at once. This change loads the ROM
using g_file_get_contents() instead, which correctly reads all data using
multiple calls to read() while also returning the loaded ROM size.

Signed-off-by: Gregor Haas <gregorhaas1997@gmail.com>
---
 hw/core/loader.c | 30 +++++-------------------------
 1 file changed, 5 insertions(+), 25 deletions(-)

diff --git a/hw/core/loader.c b/hw/core/loader.c
index 2f8105d7de..44444a5714 100644
--- a/hw/core/loader.c
+++ b/hw/core/loader.c
@@ -1075,8 +1075,7 @@ ssize_t rom_add_file(const char *file, const char *fw_dir,
 {
     MachineClass *mc = MACHINE_GET_CLASS(qdev_get_machine());
     Rom *rom;
-    ssize_t rc;
-    int fd = -1;
+    g_autoptr(GError) gerr = NULL;
     char devpath[100];
 
     if (as && mr) {
@@ -1094,35 +1093,19 @@ ssize_t rom_add_file(const char *file, const char *fw_dir,
         rom->path = g_strdup(file);
     }
 
-    fd = open(rom->path, O_RDONLY | O_BINARY);
-    if (fd == -1) {
-        fprintf(stderr, "Could not open option rom '%s': %s\n",
-                rom->path, strerror(errno));
-        goto err;
-    }
-
     if (fw_dir) {
         rom->fw_dir  = g_strdup(fw_dir);
         rom->fw_file = g_strdup(file);
     }
     rom->addr     = addr;
-    rom->romsize  = lseek(fd, 0, SEEK_END);
-    if (rom->romsize == -1) {
-        fprintf(stderr, "rom: file %-20s: get size error: %s\n",
-                rom->name, strerror(errno));
+    if (!g_file_get_contents(rom->path, (gchar **) &rom->data,
+                             &rom->romsize, &gerr)) {
+        fprintf(stderr, "rom: file %-20s: error %s\n",
+                rom->name, gerr->message);
         goto err;
     }
 
     rom->datasize = rom->romsize;
-    rom->data     = g_malloc0(rom->datasize);
-    lseek(fd, 0, SEEK_SET);
-    rc = read(fd, rom->data, rom->datasize);
-    if (rc != rom->datasize) {
-        fprintf(stderr, "rom: file %-20s: read error: rc=%zd (expected %zd)\n",
-                rom->name, rc, rom->datasize);
-        goto err;
-    }
-    close(fd);
     rom_insert(rom);
     if (rom->fw_file && fw_cfg) {
         const char *basename;
@@ -1159,9 +1142,6 @@ ssize_t rom_add_file(const char *file, const char *fw_dir,
     return 0;
 
 err:
-    if (fd != -1)
-        close(fd);
-
     rom_free(rom);
     return -1;
 }
-- 
2.45.2