commit 193e51deccc62544f6423eb5e5eefc8a23aad679

 Author: Sven Schnelle <svens@linux.ibm.com>

 Date:   Thu Dec 16 12:43:54 2021 +0100

     add slurp_proc_file()

     slurp_file() cannot be used to read proc files, as they are returning

     a size of zero in stat(). Add a function slurp_proc_file() which is

     similar to slurp_file(), but doesn't require the size of the file to

     be known.

     Signed-off-by: Sven Schnelle <svens@linux.ibm.com>

     Signed-off-by: Simon Horman <horms@verge.net.au>

 diff --git a/kexec/kexec.c b/kexec/kexec.c

 index f63b36b771eb95a93f07a7c286c4974a558aec8d..f3adac517161d448552a16fd79488c1df100d356 100644

 --- a/kexec/kexec.c

 +++ b/kexec/kexec.c

 @@ -1106,6 +1106,57 @@ static void remove_parameter(char *line, const char *param_name)

  	}

  }

 +static ssize_t _read(int fd, void *buf, size_t count)

 +{

 +	ssize_t ret, offset = 0;

 +

 +	do {

 +		ret = read(fd, buf + offset, count - offset);

 +		if (ret < 0) {

 +			if ((errno == EINTR) ||	(errno == EAGAIN))

 +				continue;

 +			return ret;

 +		}

 +		offset += ret;

 +	} while (ret && offset < count);

 +

 +	return offset;

 +}

 +

 +static char *slurp_proc_file(const char *filename, size_t *len)

 +{

 +	ssize_t ret, startpos = 0;

 +	unsigned int size = 64;

 +	char *buf = NULL, *tmp;

 +	int fd;

 +

 +	fd = open(filename, O_RDONLY);

 +	if (fd == -1)

 +		return NULL;

 +

 +	do {

 +		size *= 2;

 +		tmp = realloc(buf, size);

 +		if (!tmp) {

 +			free(buf);

 +			return NULL;

 +		}

 +		buf = tmp;

 +

 +		ret = _read(fd, buf + startpos, size - startpos);

 +		if (ret < 0) {

 +			free(buf);

 +			return NULL;

 +		}

 +

 +		startpos += ret;

 +

 +	} while(ret);

 +

 +	*len = startpos;

 +	return buf;

 +}

 +

  /*

   * Returns the contents of the current command line to be used with

   * --reuse-cmdline option.  The function gets called from architecture specific