commands: add 'findstr' to get string from file

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

(quoted diff) +0 -3

-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 <[email protected]>

---
 commands/Kconfig   |    7 +++
 commands/Makefile  |    1 +
 commands/findstr.c |  138 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 146 insertions(+)
 create mode 100644 commands/findstr.c

commands/Kconfig +0 -0

index 3ef8860..a2f817a 100644

commands/Kconfig +4 -0

+	prompt "findstr"
+	help
+	  Find string in file.
+
 endmenu
 
 menu "file commands"

commands/Makefile +1 -0

index f927d21..b7c7e31 100644
@@ -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

commands/findstr.c new file +48 -0

new file mode 100644
index 0000000..37cfee3
@@ -0,0 +1,138 @@
+/*
+ * Copyright (c) 2014 Christoph Fritz <[email protected]>
+ *
+ * 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) {

commands/findstr.c new file +51 -0

+	}
+
+	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';
+

commands/Kconfig config CMD_GLOBAL · line 154

Quoted 3 lines · Christoph Fritz

commands/Kconfig +3 -0

+config CMD_FINDSTR
+	tristate
+	default n

not needed.

commands/findstr.c line 58

Quoted 12 lines

commands/findstr.c new file +12 -0

+	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.

Quoted 49 lines

commands/findstr.c new file +49 -0

+	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);
+

commands/findstr.c line 119

Quoted 5 lines

commands/findstr.c new file +5 -0

+				ret = 0;
+				goto out;
+			}
+			r--;
+		}

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

Hi Alexander

Quoted 6 lines · Alexander Aring

commands/Kconfig config CMD_GLOBAL · line 154

Quoted 3 lines · Christoph Fritz

commands/Kconfig +3 -0

+config CMD_FINDSTR
+	tristate
+	default n

not needed.

Ok

Quoted 15 lines

commands/findstr.c line 58

Quoted 12 lines

commands/findstr.c new file +12 -0

+	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.

Quoted 2 lines

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

Ok

Quoted 49 lines

Quoted 49 lines

commands/findstr.c new file +49 -0

+	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);
+

Quoted 8 lines

commands/findstr.c line 119

Quoted 5 lines

commands/findstr.c new file +5 -0

+				ret = 0;
+				goto out;
+			}
+			r--;
+		}

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

read_file() reads the whole file which can get pretty slow over an i2c link accessing an eeprom which mostly holds the configuration-string at the beginning.

Why would I want to write the file back?

Command 'findstr' can be for example used to find string

"MAC=1C:BA:8C:F3:82:BB" in file /dev/eeprom0 to set an appropriate environment variable:

 $ findstr -o 16 -l 17 -t eth0.ethaddr pcm051_eth0_MAC= /dev/eeprom0

Usage: findstr [OPTIONS] <STRING> <FILE>
Find ASCII string in file and print it

(quoted diff) +0 -3

-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 <[email protected]>

---
Changes in v2:
- fix Kconfig: 'default n' is default
- add default branch to switch
- fix search string read-buffer overlap

---
 commands/Kconfig   |    6 +++
 commands/Makefile  |    1 +
 commands/findstr.c |  140 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 147 insertions(+)
 create mode 100644 commands/findstr.c

commands/Kconfig +6 -0

index 3ef8860..a795da9 100644
@@ -149,6 +149,12 @@ config CMD_GLOBAL
 	help
 	  The global command allows to create global variables
 
+config CMD_FINDSTR
+	tristate
+	prompt "findstr"
+	help
+	  Find ASCII string in file.
+
 endmenu
 
 menu "file commands"

commands/Makefile +1 -0

index f927d21..580b137 100644
@@ -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

commands/findstr.c new file +140 -0

new file mode 100644
index 0000000..934c300
@@ -0,0 +1,140 @@
+/*
+ * Copyright (c) 2014 Christoph Fritz <[email protected]>
+ *
+ * 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>
+
+#define FINDSTR_BUF_SIZE	RW_BUF_SIZE
+
+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;
+		default:
+			return COMMAND_ERROR_USAGE;
+		}
+	}
+
+	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, FINDSTR_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 hit = idx - strlen(s);
+
+				if (lseek(fd, hit + offset, SEEK_SET) < 0) {
+					ret = -EIO;
+					goto out;
+				}
+
+				if (!len)
+					len = strlen(s);
+				r = read(fd, mem_rw_buf, len);
+				if (r != len) {
+					ret = -EIO;
+					goto out;
+				}
+
+				v[r] = '\0';
+
+				if (t)
+					setenv(t, v);
+				else
+					printf("%s\n", v);
+
+				ret = 0;
+				goto out;
+			}
+			r--;
+		}
+	}
+out:
+	close(fd);
+	return ret;
+}
+
+BAREBOX_CMD_HELP_START(findstr)
+BAREBOX_CMD_HELP_USAGE("findstr [OPTIONS] <STRING> <FILE>\n")
+BAREBOX_CMD_HELP_SHORT("Find ASCII string in file and print it\n")
+BAREBOX_CMD_HELP_OPT("-o <offset>", "set offset of string which gets printed\n")
+BAREBOX_CMD_HELP_OPT("-l <length>", "set length of string which gets printed\n")
+BAREBOX_CMD_HELP_OPT("-t <var>", "print into variable instead of stdio\n")
+BAREBOX_CMD_HELP_END
+
+BAREBOX_CMD_START(findstr)
+	.cmd		= do_findstr,
+	.usage		= "findstr [OPTIONS] <STRING> <FILE>",
+	BAREBOX_CMD_HELP(cmd_findstr_help)
+BAREBOX_CMD_END

Signature · 7 lines

1.7.10.4


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Quoted 1 line · On Wed, 21 May 2014 10:02:42 +0200 Christoph Fritz <[email protected]>…

Command 'findstr' can be for example used to find string

We already have some commands with string.h style names:
memcmp, memcpy, memset

Can we use 'strstr' name for your new command?

Another proposition:
can we add <offset from file start> and <no more N characters to
search> parameters?

Using these parameters you can speed up your search and use your command with /dev/mem.

Review

Quoted 10 lines

"MAC=1C:BA:8C:F3:82:BB" in file /dev/eeprom0 to set an appropriate environment variable:

 $ findstr -o 16 -l 17 -t eth0.ethaddr pcm051_eth0_MAC= /dev/eeprom0

Usage: findstr [OPTIONS] <STRING> <FILE>
Find ASCII string in file and print it

(quoted diff) +0 -3

-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

Quoted 6 lines · Christoph Fritz

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

Review

Quoted 5 lines

Usage: findstr [OPTIONS] <STRING> <FILE>
Find string in file and print it

(quoted diff) +0 -3

-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

I wonder how useful such a command is. I mean normally I would expect a MAC address to be stored in binary format and not ASCII.

Matching 'MAC' (what about the '='?) seems not very robust.

What about strings with dynamic lengths?

If the command is primarily intended for the MAC address then maybe a more dedicated command or a piece of code called from board code is more robust.

If the command is intended as a general
eeprom-variable-store then I think it's not flexible enough.