[PATCH] hv/hv_kvp_daemon: Enable debug logs for hv_kvp_daemon

[Shradha Gupta <shradhagupta@linux.microsoft.com>]

Allow the KVP daemon to log the KVP updates triggered in the VM
with a new debug flag(-d).
When the daemon is started with this flag, it logs updates and debug
information in /var/log/kvp_debug_file.log. This information comes
in handy for debugging issues where the key-value pairs for certain
pools show mismatch/incorrect values.

Signed-off-by: Shradha Gupta <shradhagupta@linux.microsoft.com>
---
 tools/hv/hv_kvp_daemon.c | 120 ++++++++++++++++++++++++++++++++++++---
 1 file changed, 112 insertions(+), 8 deletions(-)

diff --git a/tools/hv/hv_kvp_daemon.c b/tools/hv/hv_kvp_daemon.c
index 04ba035d67e9..1f8b02b17356 100644
--- a/tools/hv/hv_kvp_daemon.c
+++ b/tools/hv/hv_kvp_daemon.c
@@ -41,6 +41,7 @@
 #include <net/if.h>
 #include <limits.h>
 #include <getopt.h>
+#include <time.h>
 
 /*
  * KVP protocol: The user mode component first registers with the
@@ -83,6 +84,7 @@ enum {
 };
 
 static int in_hand_shake;
+static int debug_enabled;
 
 static char *os_name = "";
 static char *os_major = "";
@@ -91,6 +93,7 @@ static char *processor_arch;
 static char *os_build;
 static char *os_version;
 static char *lic_version = "Unknown version";
+static char debug_file[PATH_MAX];
 static char full_domain_name[HV_KVP_EXCHANGE_MAX_VALUE_SIZE];
 static struct utsname uts_buf;
 
@@ -99,6 +102,7 @@ static struct utsname uts_buf;
  */
 
 #define KVP_CONFIG_LOC	"/var/lib/hyperv"
+#define KVP_DEBUG_LOC	"/var/log/"
 
 #ifndef KVP_SCRIPTS_PATH
 #define KVP_SCRIPTS_PATH "/usr/libexec/hypervkvpd/"
@@ -153,6 +157,16 @@ static void kvp_release_lock(int pool)
 	}
 }
 
+static void convert_tm_to_string(char *tm_str, size_t tm_str_size)
+{
+	struct tm tm;
+	time_t t;
+
+	time(&t);
+	gmtime_r(&t, &tm);
+	strftime(tm_str, tm_str_size, "%Y-%m-%dT%H:%M:%S", &tm);
+}
+
 static void kvp_update_file(int pool)
 {
 	FILE *filep;
@@ -183,6 +197,45 @@ static void kvp_update_file(int pool)
 	kvp_release_lock(pool);
 }
 
+static void kvp_dump_initial_pools(int pool)
+{
+	FILE *debug_filep;
+	char tm_str[50];
+	int i, ret;
+
+	convert_tm_to_string(tm_str, sizeof(tm_str));
+
+	debug_filep = fopen(debug_file, "a");
+	if (!debug_filep) {
+		syslog(LOG_ERR, "Failed to open file: %s, pool: %d; error: %d%s",
+		       debug_file, pool, errno, strerror(errno));
+		return;
+	}
+
+	ret = fprintf(debug_filep, "===Start dumping the contents on pool %d ===\n",
+		      pool);
+	if (ret <= 0) {
+		syslog(LOG_ERR, "Failed to write to kvp debug file: %d", pool);
+		fclose(debug_filep);
+		return;
+	}
+
+	for (i = 0; i < kvp_file_info[pool].num_records; i++) {
+		ret = fprintf(debug_filep, "[%s]: pool: %d, %d/%d key=%s val=%s\n",
+			      tm_str, pool, i, kvp_file_info[pool].num_records,
+			      kvp_file_info[pool].records[i].key,
+			      kvp_file_info[pool].records[i].value);
+
+		if (ret <= 0) {
+			syslog(LOG_ERR, "Failed to write to kvp debug file: pool=%d, i=%u/%u",
+			       pool, i, kvp_file_info[pool].num_records);
+			break;
+		}
+	}
+
+	fclose(debug_filep);
+}
+
 static void kvp_update_mem_state(int pool)
 {
 	FILE *filep;
@@ -270,6 +323,8 @@ static int kvp_file_init(void)
 			return 1;
 		kvp_file_info[i].num_records = 0;
 		kvp_update_mem_state(i);
+		if (debug_enabled)
+			kvp_dump_initial_pools(i);
 	}
 
 	return 0;
@@ -321,14 +376,37 @@ static int kvp_key_delete(int pool, const __u8 *key, int key_size)
 static int kvp_key_add_or_modify(int pool, const __u8 *key, int key_size,
 				 const __u8 *value, int value_size)
 {
-	int i;
-	int num_records;
 	struct kvp_record *record;
+	FILE *filep = NULL;
+	int num_records;
+	char tm_str[50];
 	int num_blocks;
+	int i;
+
+	if (debug_enabled) {
+		filep = fopen(debug_file, "a");
+		if (!filep) {
+			syslog(LOG_ERR, "Failed to open file %s; error: %d",
+			       debug_file, errno);
+		} else {
+			convert_tm_to_string(tm_str, sizeof(tm_str));
+			fprintf(filep, "[%s]:%s: got a KVP: pool=%d key=%s val=%s\n",
+				__func__, tm_str, pool, key, value);
+		}
+	}
 
 	if ((key_size > HV_KVP_EXCHANGE_MAX_KEY_SIZE) ||
-		(value_size > HV_KVP_EXCHANGE_MAX_VALUE_SIZE))
+		(value_size > HV_KVP_EXCHANGE_MAX_VALUE_SIZE)) {
+		syslog(LOG_ERR, "Got a too long key or value: key=%s, val=%s",
+		       key, value);
+
+		if (filep) {
+			fprintf(filep, "[%s]: Got a too long key or value: pool=%d, key=%s, val=%s\n",
+				tm_str, pool, key, value);
+			fclose(filep);
+		}
 		return 1;
+	}
 
 	/*
 	 * First update the in-memory state.
@@ -348,6 +426,11 @@ static int kvp_key_add_or_modify(int pool, const __u8 *key, int key_size,
 		 */
 		memcpy(record[i].value, value, value_size);
 		kvp_update_file(pool);
+		if (filep) {
+			fprintf(filep, "[%s]:%s: updated: pool=%d key=%s val=%s\n",
+				__func__, tm_str, pool, key, value);
+			fclose(filep);
+		}
 		return 0;
 	}
 
@@ -359,8 +442,12 @@ static int kvp_key_add_or_modify(int pool, const __u8 *key, int key_size,
 		record = realloc(record, sizeof(struct kvp_record) *
 			 ENTRIES_PER_BLOCK * (num_blocks + 1));
 
-		if (record == NULL)
+		if (!record) {
+			if (filep)
+				fclose(filep);
+			syslog(LOG_ERR, "%s: Memory alloc failure", __func__);
 			return 1;
+		}
 		kvp_file_info[pool].num_blocks++;
 
 	}
@@ -368,6 +455,12 @@ static int kvp_key_add_or_modify(int pool, const __u8 *key, int key_size,
 	memcpy(record[i].key, key, key_size);
 	kvp_file_info[pool].records = record;
 	kvp_file_info[pool].num_records++;
+
+	if (filep) {
+		fprintf(filep, "[%s]:%s: added: pool=%d key=%s val=%s\n",
+			__func__, tm_str, pool, key, value);
+		fclose(filep);
+	}
 	kvp_update_file(pool);
 	return 0;
 }
@@ -1662,6 +1755,7 @@ void print_usage(char *argv[])
 	fprintf(stderr, "Usage: %s [options]\n"
 		"Options are:\n"
 		"  -n, --no-daemon        stay in foreground, don't daemonize\n"
+		"  -d, --debug-enabled    Enable debug logs\n"
 		"  -h, --help             print this help\n", argv[0]);
 }
 
@@ -1681,12 +1775,13 @@ int main(int argc, char *argv[])
 	int daemonize = 1, long_index = 0, opt;
 
 	static struct option long_options[] = {
-		{"help",	no_argument,	   0,  'h' },
-		{"no-daemon",	no_argument,	   0,  'n' },
-		{0,		0,		   0,  0   }
+		{"help",		no_argument,	   0,  'h' },
+		{"no-daemon",		no_argument,	   0,  'n' },
+		{"debug-enabled",	no_argument,	   0,  'd' },
+		{0,			0,		   0,  0   }
 	};
 
-	while ((opt = getopt_long(argc, argv, "hn", long_options,
+	while ((opt = getopt_long(argc, argv, "hnd", long_options,
 				  &long_index)) != -1) {
 		switch (opt) {
 		case 'n':
@@ -1695,6 +1790,9 @@ int main(int argc, char *argv[])
 		case 'h':
 			print_usage(argv);
 			exit(0);
+		case 'd':
+			debug_enabled = 1;
+			break;
 		default:
 			print_usage(argv);
 			exit(EXIT_FAILURE);
@@ -1717,6 +1815,12 @@ int main(int argc, char *argv[])
 	 */
 	kvp_get_domain_name(full_domain_name, sizeof(full_domain_name));
 
+	if (debug_enabled) {
+		sprintf(debug_file, "%s%s", KVP_DEBUG_LOC, "kvp_debug_file.log");
+		syslog(LOG_INFO, "Logging debug info in kvp_debug_file=%s",
+		       debug_file);
+	}
+
 	if (kvp_file_init()) {
 		syslog(LOG_ERR, "Failed to initialize the pools");
 		exit(EXIT_FAILURE);
-- 
2.34.1