Re: [PATCH] commands: add 'findstr' to get string from file

[Alexander Aring <alex.aring@gmail.com>]

On Tue, May 20, 2014 at 07:27:55PM +0200, Christoph Fritz wrote:
> Command 'findstr' can be for example used to find the string
> "MAC=1C:BA:8C:F3:82:BB" in file /dev/eeprom0 to set the
> appropriate variable:
> 
>  $ findstr -o 4 -l 17 -t eth0.ethaddr MAC /dev/eeprom0
> 
> Usage: findstr [OPTIONS] <STRING> <FILE>
> Find string in file and print it
> -o <offset>     set offset of string which gets printed
> -l <length>     set length of string which gets printed
> -t <var>        print into variable instead of stdio
> 
> Signed-off-by: Christoph Fritz <chf.fritz@googlemail.com>
> ---
>  commands/Kconfig   |    7 +++
>  commands/Makefile  |    1 +
>  commands/findstr.c |  138 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 146 insertions(+)
>  create mode 100644 commands/findstr.c
> 
> diff --git a/commands/Kconfig b/commands/Kconfig
> index 3ef8860..a2f817a 100644
> --- a/commands/Kconfig
> +++ b/commands/Kconfig
> @@ -149,6 +149,13 @@ config CMD_GLOBAL
>  	help
>  	  The global command allows to create global variables
>  
> +config CMD_FINDSTR
> +	tristate
> +	default n
not needed.

> +	prompt "findstr"
> +	help
> +	  Find string in file.
> +
>  endmenu
>  
>  menu "file commands"
> diff --git a/commands/Makefile b/commands/Makefile
> index f927d21..b7c7e31 100644
> --- a/commands/Makefile
> +++ b/commands/Makefile
> @@ -97,3 +97,4 @@ obj-$(CONFIG_CMD_READF)		+= readf.o
>  obj-$(CONFIG_CMD_MENUTREE)	+= menutree.o
>  obj-$(CONFIG_CMD_2048)		+= 2048.o
>  obj-$(CONFIG_CMD_REGULATOR)	+= regulator.o
> +obj-$(CONFIG_CMD_FINDSTR)	+= findstr.o
> \ No newline at end of file
> diff --git a/commands/findstr.c b/commands/findstr.c
> new file mode 100644
> index 0000000..37cfee3
> --- /dev/null
> +++ b/commands/findstr.c
> @@ -0,0 +1,138 @@
> +/*
> + * Copyright (c) 2014 Christoph Fritz <chf.fritz@googlemail.com>
> + *
> + * See file CREDITS for list of people who contributed to this
> + * project.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2
> + * as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +/**
> + * @file
> + * @brief Find string in file
> + */
> +
> +#include <common.h>
> +#include <command.h>
> +#include <fs.h>
> +#include <fcntl.h>
> +#include <errno.h>
> +#include <getopt.h>
> +#include <environment.h>
> +
> +extern char *mem_rw_buf;
> +
> +/**
> + * @param[in] argc Argument count from command line
> + * @param[in] argv List of input arguments
> + */
> +static int do_findstr(int argc, char *argv[])
> +{
> +	int opt, fd, r, ret = 1;
> +	loff_t len = 0, offset = 0, idx = 0;
> +	u_char *s, *t = NULL, *v = (u_char *)mem_rw_buf;
> +	unsigned int v_idx, s_idx = 0;
> +
> +	if (argc < 2)
> +		return COMMAND_ERROR_USAGE;
> +
> +	while ((opt = getopt(argc, argv, "o:l:t:")) > 0) {
> +		switch (opt) {
> +		case 'o':
> +			offset = simple_strtoul(optarg, NULL, 0);
> +			break;
> +		case 'l':
> +			len = simple_strtoul(optarg, NULL, 0);
> +			break;
> +		case 't':
> +			t = optarg;
> +			break;
> +		}

switch case without default branch can occur compiler warnings.

You should return COMMAND_ERROR_USAGE in the default branch if non valid
parameter is given.

> +	}
> +
> +	if (argc - optind != 2)
> +		return COMMAND_ERROR_USAGE;
> +
> +	s = argv[optind];
> +
> +	fd = open(argv[optind+1], O_RDONLY);
> +	if (fd < 0)
> +		return COMMAND_ERROR_USAGE;
> +
> +	while (1) {
> +		r = read(fd, mem_rw_buf, RW_BUF_SIZE);
> +		if (r < 0) {
> +			ret = -EIO;
> +			goto out;
> +		}
> +		if (!r)
> +			break;
> +
> +		v_idx = 0;
> +
> +		while (r) {
> +			if (v[v_idx] == s[s_idx])
> +				s_idx++;
> +			else
> +				s_idx = 0;
> +
> +			idx++;
> +			v_idx++;
> +
> +			if (s_idx == strlen(s)) {	/* found */
> +				loff_t sz;
> +				loff_t hit = idx - strlen(s);
> +
> +				if (lseek(fd, hit + offset, SEEK_SET) < 0) {
> +					ret = -EIO;
> +					goto out;
> +				}
> +
> +				if (!len)
> +					len = strlen(s);
> +				sz = min_t(loff_t, len, RW_BUF_SIZE - 1);
> +				r = read(fd, mem_rw_buf, sz);
> +				if (r != sz) {
> +					ret = -EIO;
> +					goto out;
> +				}
> +
> +				v[sz] = '\0';
> +
> +				if (t)
> +					setenv(t, v);
> +				else
> +					printf("%s\n", v);
> +
> +				ret = 0;
> +				goto out;
> +			}
> +			r--;
> +		}

Why not use read_file and the awesome string function strstr and then
write the file back.

- Alex

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