[PATCH v4 05/16] Add LogMessageVerbSigSafe() for logging messages while in signal context
Chase Douglas
chase.douglas at canonical.com
Mon May 14 14:14:26 PDT 2012
Signed-off-by: Chase Douglas <chase.douglas at canonical.com>
---
Changes since v3:
* Rebased onto master
- Log writing now occurs in LogSWrite, which is now signal-safe
* Removed timestamp logging, it's not safe to get the current timestamp
* Updated pnprintf to use 21 character string for number formats
include/os.h | 54 ++++++++++++++++++++++++++
os/log.c | 120 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 170 insertions(+), 4 deletions(-)
diff --git a/include/os.h b/include/os.h
index 276eb52..8e7aedb 100644
--- a/include/os.h
+++ b/include/os.h
@@ -49,6 +49,7 @@ SOFTWARE.
#include "misc.h"
#include <stdarg.h>
+#include <stdint.h>
#include <string.h>
#define SCREEN_SAVER_ON 0
@@ -583,6 +584,8 @@ typedef enum {
X_UNKNOWN = -1 /* unknown -- this must always be last */
} MessageType;
+typedef const uint64_t log_param_t;
+
extern _X_EXPORT const char *
LogInit(const char *fname, const char *backup);
extern _X_EXPORT void
@@ -604,6 +607,9 @@ _X_ATTRIBUTE_PRINTF(3, 4);
extern _X_EXPORT void
LogMessage(MessageType type, const char *format, ...)
_X_ATTRIBUTE_PRINTF(2, 3);
+extern _X_EXPORT void
+_LogMessageVerbSigSafe(MessageType type, int verb, const char *format,
+ const log_param_t *args, int num_args);
extern _X_EXPORT void
LogVHdrMessageVerb(MessageType type, int verb,
@@ -654,4 +660,52 @@ LogPrintMarkers(void);
extern _X_EXPORT void
xorg_backtrace(void);
+#define NARG(...) (NARG_(__VA_ARGS__, RSEQ_N) - (sizeof(#__VA_ARGS__) == 1))
+#define NARG_(...) NARG__(__VA_ARGS__)
+#define NARG__( _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, N, ...) (N)
+#define RSEQ_N 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0
+
+#define ARG_N_9_(_1, _2, _3, _4, _5, _6, _7, _8, _9, N, ...) (log_param_t)(N)
+#define ARG_N_9(...) ARG_N_9_(__VA_ARGS__)
+#define ARG_N_8_(_1, _2, _3, _4, _5, _6, _7, _8, N, ...) (log_param_t)(N)
+#define ARG_N_8(...) ARG_N_8_(__VA_ARGS__)
+#define ARG_N_7_(_1, _2, _3, _4, _5, _6, _7, N, ...) (log_param_t)(N)
+#define ARG_N_7(...) ARG_N_7_(__VA_ARGS__)
+#define ARG_N_6_(_1, _2, _3, _4, _5, _6, N, ...) (log_param_t)(N)
+#define ARG_N_6(...) ARG_N_6_(__VA_ARGS__)
+#define ARG_N_5_(_1, _2, _3, _4, _5, N, ...) (log_param_t)(N)
+#define ARG_N_5(...) ARG_N_5_(__VA_ARGS__)
+#define ARG_N_4_(_1, _2, _3, _4, N, ...) (log_param_t)(N)
+#define ARG_N_4(...) ARG_N_4_(__VA_ARGS__)
+#define ARG_N_3_(_1, _2, _3, N, ...) (log_param_t)(N)
+#define ARG_N_3(...) ARG_N_3_(__VA_ARGS__)
+#define ARG_N_2_(_1, _2, N, ...) (log_param_t)(N)
+#define ARG_N_2(...) ARG_N_2_(__VA_ARGS__)
+#define ARG_N_1_(_1, N, ...) (log_param_t)(N)
+#define ARG_N_1(...) ARG_N_1_(__VA_ARGS__)
+#define ARG_N_0(N, ...) (log_param_t)(sizeof(#N) != 1 ? N : 0)
+
+/* Only 10 arguments are supported. If more are needed, update the NARG__,
+ * RSEQ_N, and ARG_N_* macros. */
+#define LogMessageVerbSigSafe(type, verb, fmt, ...) do { \
+ int _num_args = NARG(__VA_ARGS__); \
+ uint64_t _args[_num_args]; \
+_Pragma("GCC diagnostic push") \
+_Pragma("GCC diagnostic ignored \"-Wbad-function-cast\"") \
+ switch (_num_args) { \
+ case 10: _args[9] = ARG_N_9(__VA_ARGS__, RSEQ_N); \
+ case 9: _args[8] = ARG_N_8(__VA_ARGS__, RSEQ_N); \
+ case 8: _args[7] = ARG_N_7(__VA_ARGS__, RSEQ_N); \
+ case 7: _args[6] = ARG_N_6(__VA_ARGS__, RSEQ_N); \
+ case 6: _args[5] = ARG_N_5(__VA_ARGS__, RSEQ_N); \
+ case 5: _args[4] = ARG_N_4(__VA_ARGS__, RSEQ_N); \
+ case 4: _args[3] = ARG_N_3(__VA_ARGS__, RSEQ_N); \
+ case 3: _args[2] = ARG_N_2(__VA_ARGS__, RSEQ_N); \
+ case 2: _args[1] = ARG_N_1(__VA_ARGS__, RSEQ_N); \
+ case 1: _args[0] = ARG_N_0(__VA_ARGS__, RSEQ_N); \
+ } \
+_Pragma("GCC diagnostic pop") \
+ _LogMessageVerbSigSafe(type, verb, fmt, _args, _num_args); \
+} while(0)
+
#endif /* OS_H */
diff --git a/os/log.c b/os/log.c
index 5394847..8adf6cc 100644
--- a/os/log.c
+++ b/os/log.c
@@ -172,6 +172,14 @@ asm(".desc ___crashreporter_info__, 0x10");
#define X_NONE_STRING ""
#endif
+static size_t
+strlen_sigsafe(const char *s)
+{
+ size_t len;
+ for (len = 0; s[len]; len++);
+ return len;
+}
+
/*
* LogInit is called to start logging to a file. It is also called (with
* NULL arguments) when logging to a file is not wanted. It must always be
@@ -271,16 +279,90 @@ LogSetParameter(LogParameter param, int value)
}
}
-/* This function does the actual log message writes. */
+static int
+pnprintf(char *string, size_t size, const char *f, log_param_t *args,
+ int num_args)
+{
+ int f_idx = 0;
+ int s_idx = 0;
+ int p_idx = 0;
+ int f_len = strlen_sigsafe(f);
+ char *string_arg;
+ char number[21];
+ int p_len;
+ int i;
+
+ for (; f_idx < f_len && s_idx < size - 1; f_idx++) {
+ if (f[f_idx] != '%' || p_idx >= num_args) {
+ string[s_idx++] = f[f_idx];
+ continue;
+ }
+
+ switch (f[++f_idx]) {
+ case 's':
+ string_arg = (char *)args[p_idx++];
+ p_len = strlen_sigsafe(string_arg);
+
+ for (i = 0; i < p_len && s_idx < size - 1; i++)
+ string[s_idx++] = string_arg[i];
+ break;
+
+ case 'u':
+ FormatUInt64((uint64_t)args[p_idx++], number);
+ p_len = strlen_sigsafe(number);
+
+ for (i = 0; i < p_len && s_idx < size - 1; i++)
+ string[s_idx++] = number[i];
+ break;
+
+ case 'p':
+ string[s_idx++] = '0';
+ if (s_idx < size - 1)
+ string[s_idx++] = 'x';
+ /* Intentional fall-through */
+
+ case 'x':
+ FormatUInt64Hex((uint64_t)args[p_idx++], number);
+ p_len = strlen_sigsafe(number);
+
+ for (i = 0; i < p_len && s_idx < size - 1; i++)
+ string[s_idx++] = number[i];
+ break;
+
+ default:
+ p_idx++;
+ string[s_idx++] = '%';
+ if (s_idx < size - 1)
+ string[s_idx++] = f[f_idx];
+ break;
+ }
+ }
+
+ string[s_idx] = '\0';
+
+ return s_idx;
+}
+
+/* This function does the actual log message writes. It must be signal safe.
+ * When attempting to call non-signal-safe functions, guard them with a check
+ * of the inSignalContext global variable. */
static void
LogSWrite(int verb, const char *buf, size_t len, Bool end_line)
{
static Bool newline = TRUE;
if (verb < 0 || logVerbosity >= verb)
- fwrite(buf, len, 1, stderr);
+ write(2, buf, len);
+
if (verb < 0 || logFileVerbosity >= verb) {
- if (logFile) {
+ if (inSignalContext && logFileFd >= 0) {
+ write(logFileFd, buf, len);
+#ifdef WIN32
+ if (logFlush && logSync)
+ fsync(logFileFd);
+#endif
+ }
+ else if (!inSignalContext && logFile) {
if (newline)
fprintf(logFile, "[%10.3f] ", GetTimeInMillis() / 1000.0);
newline = end_line;
@@ -293,7 +375,7 @@ LogSWrite(int verb, const char *buf, size_t len, Bool end_line)
#endif
}
}
- else if (needBuffer) {
+ else if (!inSignalContext && needBuffer) {
if (len > bufferUnused) {
bufferSize += 1024;
bufferUnused += 1024;
@@ -415,6 +497,36 @@ LogMessage(MessageType type, const char *format, ...)
va_end(ap);
}
+/* Log a message using only signal safe functions. */
+void
+_LogMessageVerbSigSafe(MessageType type, int verb, const char *format,
+ const log_param_t *args, int num_args)
+{
+ const char *type_str;
+ char buf[1024];
+ int len;
+ Bool newline;
+
+ type_str = LogMessageTypeVerbString(type, verb);
+ if (!type_str)
+ return;
+
+ /* if type_str is not "", prepend it and ' ', to message */
+ if (type_str[0] != '\0') {
+ LogSWrite(verb, type_str, strlen_sigsafe(type_str), FALSE);
+ LogSWrite(verb, " ", 1, FALSE);
+ }
+
+ len = pnprintf(buf, sizeof(buf), format, args, num_args);
+
+ /* Force '\n' at end of truncated line */
+ if (sizeof(buf) - len == 1)
+ buf[len - 1] = '\n';
+
+ newline = (buf[len - 1] == '\n');
+ LogSWrite(verb, buf, len, newline);
+}
+
void
LogVHdrMessageVerb(MessageType type, int verb, const char *msg_format,
va_list msg_args, const char *hdr_format, va_list hdr_args)
--
1.7.9.5
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