[Qemu-devel] [PATCH] Add support for using directory as initrd

[Kasper Dupont <kasperd@fjtcb.17.jan.2016.kasperd.net>]

Signed-off-by: Kasper Dupont <kasperd@fjtcb.17.jan.2016.kasperd.net>
---
 hw/core/loader.c    | 71 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 hw/i386/pc.c        |  6 +++--
 include/hw/loader.h |  1 +
 3 files changed, 76 insertions(+), 2 deletions(-)

diff --git a/hw/core/loader.c b/hw/core/loader.c
index 3a57415..6047486 100644
--- a/hw/core/loader.c
+++ b/hw/core/loader.c
@@ -54,6 +54,7 @@
 #include "exec/address-spaces.h"
 #include "hw/boards.h"
 
+#include <error.h>
 #include <zlib.h>
 
 static int roms_loaded;
@@ -164,6 +165,76 @@ void pstrcpy_targphys(const char *name, hwaddr dest, int buf_size,
     }
 }
 
+/* return the size or -1 if error */
+int load_initrd(const char *filename, uint8_t **addr)
+{
+    pid_t child = 0;
+    int fd, size = 0, buffer_size = 4096;
+    fd = open(filename, O_RDONLY | O_BINARY);
+    if (fd < 0) {
+        return -1;
+    }
+
+    *addr = malloc(buffer_size);
+
+    while (*addr) {
+        int bytes_read = read(fd, (*addr) + size, buffer_size - size);
+
+        if (bytes_read == 0) {
+            close(fd);
+            if (child) {
+                waitpid(child, NULL, 0);
+            }
+            return size;
+        }
+
+        if (bytes_read > 0) {
+            size += bytes_read;
+        } else {
+            int pipefd[2];
+
+            if (errno != EISDIR) {
+                return -1;
+            }
+
+            assert(!child);
+
+            if (pipe(pipefd)) {
+                return -1;
+            }
+
+            child = fork();
+            if (child == -1) {
+                return -1;
+            }
+
+            if (!child) {
+                if (fchdir(fd)) {
+                    error(1, errno, "fchdir failed");
+                }
+                if (dup2(pipefd[1], 1) == -1) {
+                    error(1, errno, "dup2 failed");
+                }
+                execlp("/bin/sh", "/bin/sh", "-c",
+                       "find . | cpio --quiet -R 0:0 -o -H newc",
+                       NULL);
+                error(1, errno, "/bin/sh");
+            }
+
+            close(fd);
+            close(pipefd[1]);
+            fd = pipefd[0];
+        }
+
+        if (size == buffer_size) {
+            buffer_size <<= 1;
+            *addr = realloc(*addr, buffer_size);
+        }
+    }
+
+    return -1;
+}
+
 /* A.OUT loader */
 
 struct exec
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index b28bac4..d9e1596 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -953,12 +953,13 @@ static void load_linux(PCMachineState *pcms,
 
     /* load initrd */
     if (initrd_filename) {
+        uint8_t *initrd_load_buffer;
         if (protocol < 0x200) {
             fprintf(stderr, "qemu: linux kernel too old to load a ram disk\n");
             exit(1);
         }
 
-        initrd_size = get_image_size(initrd_filename);
+        initrd_size = load_initrd(initrd_filename, &initrd_load_buffer);
         if (initrd_size < 0) {
             fprintf(stderr, "qemu: error reading initrd %s: %s\n",
                     initrd_filename, strerror(errno));
@@ -968,7 +969,8 @@ static void load_linux(PCMachineState *pcms,
         initrd_addr = (initrd_max-initrd_size) & ~4095;
 
         initrd_data = g_malloc(initrd_size);
-        load_image(initrd_filename, initrd_data);
+        memcpy(initrd_data, initrd_load_buffer, initrd_size);
+        free(initrd_load_buffer);
 
         fw_cfg_add_i32(fw_cfg, FW_CFG_INITRD_ADDR, initrd_addr);
         fw_cfg_add_i32(fw_cfg, FW_CFG_INITRD_SIZE, initrd_size);
diff --git a/include/hw/loader.h b/include/hw/loader.h
index f7b43ab..4fb4773 100644
--- a/include/hw/loader.h
+++ b/include/hw/loader.h
@@ -13,6 +13,7 @@
  */
 int get_image_size(const char *filename);
 int load_image(const char *filename, uint8_t *addr); /* deprecated */
+int load_initrd(const char *filename, uint8_t **addr);
 ssize_t load_image_size(const char *filename, void *addr, size_t size);
 int load_image_targphys(const char *filename, hwaddr,
                         uint64_t max_sz);
-- 
1.9.1