[lttng-dev] [PATCH lttng-tools] lttng cli: Accept human readable sizes for --subbuf-size

[Simon Marchi]

--subbuf-size accepts sizes such as:

- 123 -> 123
- 123k or 123K -> 123 * 1024
- 123m or 123M -> 123 * 1024 * 1024
- 123g or 123G -> 123 * 1024 * 1024 * 1024

It uses the new parse_human_size function, which could probably be used
at other places, such as tracefile size.

I wanted to add some unit tests for parse_human_size, but the current
test system does not make it easy. They will come later.

Signed-off-by: Simon Marchi <simon.marchi at polymtl.ca>
---
 src/bin/lttng/commands/enable_channels.c |   18 +++++-
 src/bin/lttng/utils.c                    |   96 +++++++++++++++++++++++++++++-
 src/bin/lttng/utils.h                    |    2 +
 3 files changed, 113 insertions(+), 3 deletions(-)

diff --git a/src/bin/lttng/commands/enable_channels.c b/src/bin/lttng/commands/enable_channels.c
index d026af4..f71bda5 100644
--- a/src/bin/lttng/commands/enable_channels.c
+++ b/src/bin/lttng/commands/enable_channels.c
@@ -289,6 +289,7 @@ int cmd_enable_channels(int argc, const char **argv)
 	int opt, ret = CMD_SUCCESS;
 	static poptContext pc;
 	char *session_name = NULL;
+	char *opt_arg = NULL;
 
 	init_channel_config();
 
@@ -309,8 +310,21 @@ int cmd_enable_channels(int argc, const char **argv)
 			DBG("Channel set to overwrite");
 			break;
 		case OPT_SUBBUF_SIZE:
-			/* TODO Replace atol with strtol and check for errors */
-			chan.attr.subbuf_size = atol(poptGetOptArg(pc));
+			/* Parse the size */
+			opt_arg = poptGetOptArg(pc);
+			if (!parse_human_size(opt_arg, &chan.attr.subbuf_size)) {
+				ERR("Wrong format for subbuf size parameter: %s", opt_arg);
+				ret = CMD_ERROR;
+				goto end;
+			}
+
+			/* Check if power of 2 */
+			if ((chan.attr.subbuf_size - 1) & chan.attr.subbuf_size) {
+				ERR("The subbuf size is not a power of 2: %" PRIu64 " (%s)", chan.attr.subbuf_size, opt_arg);
+				ret = CMD_ERROR;
+				goto end;
+			}
+
 			DBG("Channel subbuf size set to %" PRIu64, chan.attr.subbuf_size);
 			break;
 		case OPT_NUM_SUBBUF:
diff --git a/src/bin/lttng/utils.c b/src/bin/lttng/utils.c
index b7f5170..a21f00f 100644
--- a/src/bin/lttng/utils.c
+++ b/src/bin/lttng/utils.c
@@ -16,9 +16,10 @@
  */
 
 #define _GNU_SOURCE
-#include <stdlib.h>
 #include <ctype.h>
 #include <limits.h>
+#include <regex.h>
+#include <stdlib.h>
 
 #include <common/error.h>
 
@@ -77,3 +78,96 @@ void list_cmd_options(FILE *ofp, struct poptOption *options)
 		}
 	}
 }
+
+/**
+ * Prints the error message corresponding to a regex error code.
+ *
+ * @param errcode	The error code.
+ * @param regex		The regex object that produced the error code.
+ */
+void regex_print_error(int errcode, regex_t *regex)
+{
+	/* Get length of error message and allocate accordingly */
+	size_t length = regerror(errcode, regex, NULL, 0);
+	char *buffer = malloc(length);
+
+	if (buffer) {
+		/* Get and print error message */
+		regerror(errcode, regex, buffer, length);
+		ERR("%s\n", buffer);
+		free(buffer);
+	}
+}
+
+/**
+ * Parse a string that represents a size in human readable format. It
+ * support decimal integers suffixed by 'k', 'K', 'm', 'M', g' or 'G'.
+ *
+ * The suffix multiply the integer by:
+ * 'k' or 'K': 1024
+ * 'm' or 'M': 1024 * 1024
+ * 'g' or 'G': 1024 * 1024 * 1024
+ *
+ * @param str	The string to parse.
+ * @param size	Pointer to a size_t that will be filled with the
+ * 	  	resulting size.
+ *
+ * @return	1 on success, 0 on failure.
+ */
+uint64_t parse_human_size(char *str, size_t *size)
+{
+	regex_t regex;
+	int ret;
+
+	if (!str)
+		return 0;
+
+	/* Compile regex */
+	ret = regcomp(&regex, "^[0-9][0-9]*\\([kmg]\\{0,1\\}\\)$", REG_ICASE);
+
+	/* Check for regex error */
+	if (ret != 0) {
+		regex_print_error(ret, &regex);
+
+		regfree(&regex);
+		return 0;
+	}
+
+	const int nmatch = 2;
+	regmatch_t matches[nmatch];
+
+	/* Match regex */
+	ret = regexec(&regex, str, nmatch, matches, 0);
+	if (ret == 0) {
+		/* There is a match ! */
+		ret = 1;
+
+		*size = atol(str);
+
+		/* Check if there is a suffix */
+		regmatch_t suffix_match = matches[1];
+		if (suffix_match.rm_eo - suffix_match.rm_so > 0) {
+			switch (*(str + suffix_match.rm_so)) {
+			case 'k':
+			case 'K':
+				*size = *size * 1024;
+				break;
+			case 'm':
+			case 'M':
+				*size = *size * 1024 * 1024;
+				break;
+			case 'g':
+			case 'G':
+				*size = *size * 1024 * 1024 * 1024;
+				break;
+			}
+		}
+
+		regfree(&regex);
+		return 1;
+	} else {
+		/* There is no match (or error) */
+		regfree(&regex);
+		return 0;
+	}
+}
diff --git a/src/bin/lttng/utils.h b/src/bin/lttng/utils.h
index 9f7bfcc..20ebd68 100644
--- a/src/bin/lttng/utils.h
+++ b/src/bin/lttng/utils.h
@@ -19,8 +19,10 @@
 #define _LTTNG_UTILS_H
 
 #include <popt.h>
+#include <stdint.h>
 
 char *get_session_name(void);
 void list_cmd_options(FILE *ofp, struct poptOption *options);
+uint64_t parse_human_size(char *str, size_t *size);
 
 #endif /* _LTTNG_UTILS_H */
-- 
1.7.1