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>
---
v10:
  * fix overflow [Max]
  * remove casting to bool [Max, Eric]
  * fix wording [Max]

v9:
  * replace flag cast to int with bool [Eric]
  * fix the error message [Eric]
  * use qemu_io_free instead of qemu_vfree [Eric]
  * add function description [Eric]

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 | 99 +++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 93 insertions(+), 6 deletions(-)

diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
index 09750a23ce..f411811d95 100644
--- a/qemu-io-cmds.c
+++ b/qemu-io-cmds.c
@@ -351,6 +351,79 @@ static void qemu_io_free(void *p)
     qemu_vfree(p);
 }
 
+/*
+ * qemu_io_alloc_from_file()
+ *
+ * Allocates the buffer and populates it with the content of the given file
+ * up to @len bytes. If the file length is less than @len, then the buffer
+ * is populated with the file content cyclically.
+ *
+ * @blk - the block backend where the buffer content is going to be written to
+ * @len - the buffer length
+ * @file_name - the file to read the content from
+ *
+ * Returns: the buffer pointer on success
+ *          NULL on error
+ */
+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;
+        buf += MISALIGN_OFFSET;
+        len -= 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_io_free(buf_origin);
+    return NULL;
+}
+
 static void dump_buffer(const void *buffer, int64_t offset, int64_t len)
 {
     uint64_t i;
@@ -949,6 +1022,7 @@ 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 +1039,7 @@ 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 +1048,7 @@ 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 +1057,9 @@ 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 +1095,10 @@ 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 +1130,9 @@ 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 (zflag + Pflag + sflag > 1) {
+        printf("Only one of -z, -P, and -s "
+               "can be specified at the same time\n");
         return -EINVAL;
     }
 
@@ -1088,7 +1168,14 @@ 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 8/20/19 11:46 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>
> ---

> @@ -983,8 +1057,9 @@ 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) {

This one looks odd (I would have preserved ordering by sticking s:
between q and u).  But a maintainer could fix that.

>          switch (c) {
>          case 'b':
>              bflag = true;
> @@ -1020,6 +1095,10 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
>          case 'z':
>              zflag = true;
>              break;
> +        case 's':
> +            sflag = true;
> +            file_name = optarg;
> +            break;

Likewise, sorting the cases in the same order as the getopt() listing
helps in finding code during later edits.

> @@ -1088,7 +1168,14 @@ 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);
> +        }

Pre-existing, but it is odd that qemu_io_alloc() exit()s rather than
returning NULL on huge allocation requests that can't be met.  (Then
again, we have an early exit on any length > 2G, and 2G allocations tend
to succeed on modern development machines).  Perhaps it would be nice to
teach qemu-io to use blk_try_blockalign for more graceful handling even
on 32-bit platforms, but that's not the problem of your patch.

Option ordering is minor enough that I'm fine giving:

Reviewed-by: Eric Blake <eblake@redhat.com>

Now, to figure out which maintainer should take it.  Perhaps you want to
add a patch 2/1 that adds an iotest using this new mode, to a) ensure it
doesn't regress, and b) makes it reasonable to take in through the
iotest tree.

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

On 20.08.19 19:24, Eric Blake wrote:
> On 8/20/19 11:46 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>
>> ---
> 
>> @@ -983,8 +1057,9 @@ 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) {
> 
> This one looks odd (I would have preserved ordering by sticking s:
> between q and u).  But a maintainer could fix that.
> 
>>          switch (c) {
>>          case 'b':
>>              bflag = true;
>> @@ -1020,6 +1095,10 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
>>          case 'z':
>>              zflag = true;
>>              break;
>> +        case 's':
>> +            sflag = true;
>> +            file_name = optarg;
>> +            break;
> 
> Likewise, sorting the cases in the same order as the getopt() listing
> helps in finding code during later edits.

But it is in order of the getopt() listing. ;-)

>> @@ -1088,7 +1168,14 @@ 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);
>> +        }
> 
> Pre-existing, but it is odd that qemu_io_alloc() exit()s rather than
> returning NULL on huge allocation requests that can't be met.  (Then
> again, we have an early exit on any length > 2G, and 2G allocations tend
> to succeed on modern development machines).  Perhaps it would be nice to
> teach qemu-io to use blk_try_blockalign for more graceful handling even
> on 32-bit platforms, but that's not the problem of your patch.

Then again, this is qemu-io.  Printing an error instead of just aborting
doesn’t really help anyone.

Also, the code would be wrong without an early exit on a length >
INT_MAX.  (Because pattern_len is an int, so the result of fread() might
overflow otherwise, which would be bad.)

(I just noticed that fread() might do a short read, but let’s just
ignore this at this point.)

> Option ordering is minor enough that I'm fine giving:
> 
> Reviewed-by: Eric Blake <eblake@redhat.com>
> 
> Now, to figure out which maintainer should take it.  Perhaps you want to
> add a patch 2/1 that adds an iotest using this new mode, to a) ensure it
> doesn't regress, and b) makes it reasonable to take in through the
> iotest tree.

Adding a test does not seem to bad of an idea, but I don’t see how that
would clarify things.  Both qemu-io and the iotests are part of the
block layer core:

$ scripts/get_maintainer.pl -f qemu-io-cmds.c
Kevin Wolf <kwolf@redhat.com> (supporter:Block layer core)
Max Reitz <mreitz@redhat.com> (supporter:Block layer core)
qemu-block@nongnu.org (open list:Block layer core)
qemu-devel@nongnu.org (open list:All patches CC here)

$ scripts/get_maintainer.pl -f tests/qemu-iotests
Kevin Wolf <kwolf@redhat.com> (supporter:Block layer core)
Max Reitz <mreitz@redhat.com> (supporter:Block layer core)
qemu-block@nongnu.org (open list:Block layer core)
qemu-devel@nongnu.org (open list:All patches CC here)


So we only need to figure out whether it should be Kevin or me to take
it; but Kevin is on PTO, so that decision is simple. :-)

Therefor, I’ve changed the optstring (and switch case) order to be
alphabetical, and applied the patch to my block branch:

https://git.xanclic.moe/XanClic/qemu/commits/branch/block

Thanks for the patch and the review,

Max


(I wouldn’t mind an iotest, but well.  qemu-io itself is a testing
utility, so I don’t deem it important to test it.)

On 8/20/19 1:24 PM, Eric Blake wrote:
> On 8/20/19 11:46 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>
>> ---
> 
>> @@ -983,8 +1057,9 @@ 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) {
> 
> This one looks odd (I would have preserved ordering by sticking s:
> between q and u).  But a maintainer could fix that.
> 
>>          switch (c) {
>>          case 'b':
>>              bflag = true;
>> @@ -1020,6 +1095,10 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
>>          case 'z':
>>              zflag = true;
>>              break;
>> +        case 's':
>> +            sflag = true;
>> +            file_name = optarg;
>> +            break;
> 
> Likewise, sorting the cases in the same order as the getopt() listing
> helps in finding code during later edits.
> 
>> @@ -1088,7 +1168,14 @@ 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);
>> +        }
> 
> Pre-existing, but it is odd that qemu_io_alloc() exit()s rather than
> returning NULL on huge allocation requests that can't be met.  (Then
> again, we have an early exit on any length > 2G, and 2G allocations tend
> to succeed on modern development machines).  Perhaps it would be nice to
> teach qemu-io to use blk_try_blockalign for more graceful handling even
> on 32-bit platforms, but that's not the problem of your patch.
> 
> Option ordering is minor enough that I'm fine giving:
> 
> Reviewed-by: Eric Blake <eblake@redhat.com>
> 
> Now, to figure out which maintainer should take it.  Perhaps you want to
> add a patch 2/1 that adds an iotest using this new mode, to a) ensure it
> doesn't regress, and b) makes it reasonable to take in through the
> iotest tree.
> 

Yes, this is a good idea. I'm sure over time we'll pick up uses of
pattern writing that will strengthen the the regression testing of the
feature, but for now a simple test case will help ensure it.

(It'll also help "document" how to use the feature for other test writers.)

Thanks!