The patch allows to provide a pattern file for write
command. There was no similar ability before.

Signed-off-by: Denis Plotnikov <dplotnikov@virtuozzo.com>
---
v8: fix according to Max's comments
  * get rid of unnecessary buffer for the pattern
  * buffer allocation just in bytes
  * take into account the missalign offset
  * don't copy file name
  * changed char* to const char* in input params

v7:
  * fix variable naming
  * make code more readable
  * extend help for write command

v6:
  * the pattern file is read once to reduce io

v5:
  * file name initiated with null to make compilers happy

v4:
  * missing signed-off clause added

v3:
  * missing file closing added
  * exclusive flags processing changed
  * buffer void* converted to char* to fix pointer arithmetics
  * file reading error processing added
---
 qemu-io-cmds.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 77 insertions(+), 6 deletions(-)

diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
index 09750a23ce..940271ea00 100644
--- a/qemu-io-cmds.c
+++ b/qemu-io-cmds.c
@@ -343,6 +343,63 @@ static void *qemu_io_alloc(BlockBackend *blk, size_t len, int pattern)
     return buf;
 }
 
+static void *qemu_io_alloc_from_file(BlockBackend *blk, size_t len,
+                                     const char *file_name)
+{
+    char *buf, *buf_origin;
+    FILE *f = fopen(file_name, "r");
+    int pattern_len;
+
+    if (!f) {
+        perror(file_name);
+        return NULL;
+    }
+
+    if (qemuio_misalign) {
+        len += MISALIGN_OFFSET;
+    }
+
+    buf_origin = buf = blk_blockalign(blk, len);
+
+    if (qemuio_misalign) {
+        buf_origin += MISALIGN_OFFSET;
+    }
+
+    pattern_len = fread(buf_origin, 1, len, f);
+
+    if (ferror(f)) {
+        perror(file_name);
+        goto error;
+    }
+
+    if (pattern_len == 0) {
+        fprintf(stderr, "%s: file is empty\n", file_name);
+        goto error;
+    }
+
+    fclose(f);
+
+    if (len > pattern_len) {
+        len -= pattern_len;
+        buf += pattern_len;
+
+        while (len > 0) {
+            size_t len_to_copy = MIN(pattern_len, len);
+
+            memcpy(buf, buf_origin, len_to_copy);
+
+            len -= len_to_copy;
+            buf += len_to_copy;
+        }
+    }
+
+    return buf_origin;
+
+error:
+    qemu_vfree(buf_origin);
+    return NULL;
+}
+
 static void qemu_io_free(void *p)
 {
     if (qemuio_misalign) {
@@ -949,6 +1006,7 @@ static void write_help(void)
 " -n, -- with -z, don't allow slow fallback\n"
 " -p, -- ignored for backwards compatibility\n"
 " -P, -- use different pattern to fill file\n"
+" -s, -- use a pattern file to fill the write buffer\n"
 " -C, -- report statistics in a machine parsable format\n"
 " -q, -- quiet mode, do not show I/O statistics\n"
 " -u, -- with -z, allow unmapping\n"
@@ -965,7 +1023,7 @@ static const cmdinfo_t write_cmd = {
     .perm       = BLK_PERM_WRITE,
     .argmin     = 2,
     .argmax     = -1,
-    .args       = "[-bcCfnquz] [-P pattern] off len",
+    .args       = "[-bcCfnquz] [-P pattern | -s source_file] off len",
     .oneline    = "writes a number of bytes at a specified offset",
     .help       = write_help,
 };
@@ -974,7 +1032,7 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
 {
     struct timeval t1, t2;
     bool Cflag = false, qflag = false, bflag = false;
-    bool Pflag = false, zflag = false, cflag = false;
+    bool Pflag = false, zflag = false, cflag = false, sflag = false;
     int flags = 0;
     int c, cnt, ret;
     char *buf = NULL;
@@ -983,8 +1041,9 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
     /* Some compilers get confused and warn if this is not initialized.  */
     int64_t total = 0;
     int pattern = 0xcd;
+    const char *file_name = NULL;
 
-    while ((c = getopt(argc, argv, "bcCfnpP:quz")) != -1) {
+    while ((c = getopt(argc, argv, "bcCfnpP:quzs:")) != -1) {
         switch (c) {
         case 'b':
             bflag = true;
@@ -1020,6 +1079,10 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
         case 'z':
             zflag = true;
             break;
+        case 's':
+            sflag = true;
+            file_name = optarg;
+            break;
         default:
             qemuio_command_usage(&write_cmd);
             return -EINVAL;
@@ -1051,8 +1114,9 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
         return -EINVAL;
     }
 
-    if (zflag && Pflag) {
-        printf("-z and -P cannot be specified at the same time\n");
+    if ((int)zflag + (int)Pflag + (int)sflag > 1) {
+        printf("Only one of -z, -P, and -s"
+               "can be specified at the same time\n");
         return -EINVAL;
     }
 
@@ -1088,7 +1152,14 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
     }
 
     if (!zflag) {
-        buf = qemu_io_alloc(blk, count, pattern);
+        if (sflag) {
+            buf = qemu_io_alloc_from_file(blk, count, file_name);
+            if (!buf) {
+                return -EINVAL;
+            }
+        } else {
+            buf = qemu_io_alloc(blk, count, pattern);
+        }
     }
 
     gettimeofday(&t1, NULL);
-- 
2.17.0

On 8/7/19 2:06 AM, Denis Plotnikov wrote:
> The patch allows to provide a pattern file for write
> command. There was no similar ability before.
> 
> Signed-off-by: Denis Plotnikov <dplotnikov@virtuozzo.com>
> ---

>  
> +static void *qemu_io_alloc_from_file(BlockBackend *blk, size_t len,
> +                                     const char *file_name)
> +{

No comment on the usage of this function? Existing practice in this file
is not the best, but new code can do better.

> +    char *buf, *buf_origin;
> +    FILE *f = fopen(file_name, "r");
> +    int pattern_len;
> +
> +    if (!f) {
> +        perror(file_name);
> +        return NULL;
> +    }
> +
> +    if (qemuio_misalign) {
> +        len += MISALIGN_OFFSET;
> +    }
> +
> +    buf_origin = buf = blk_blockalign(blk, len);
> +
> +    if (qemuio_misalign) {
> +        buf_origin += MISALIGN_OFFSET;

Here, you are changing where you point...

> +    }
> +
> +    pattern_len = fread(buf_origin, 1, len, f);
> +
> +    if (ferror(f)) {
> +        perror(file_name);
> +        goto error;
> +    }

...but if you fail here...


> +
> +error:
> +    qemu_vfree(buf_origin);

...then you free the wrong pointer.  This MUST use
qemu_io_free(buf_origin) (the same as write_f correctly does with the
misaligned pointer that you return on success).

> @@ -1051,8 +1114,9 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
>          return -EINVAL;
>      }
>  
> -    if (zflag && Pflag) {
> -        printf("-z and -P cannot be specified at the same time\n");
> +    if ((int)zflag + (int)Pflag + (int)sflag > 1) {

The casts to int are not necessary.  Adding two bools promotes to int
naturally.

> +        printf("Only one of -z, -P, and -s"
> +               "can be specified at the same time\n");

Missing a space; you don't want your user to see "and -scan be".

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org