cherry-pick: Suggest a better method to retain authorship

diff --git a/trace.c b/trace.c
index 90847c3fd84b4cc065db8ef41d1010991fe4bafc..27fef868c4e2276638873cbda7d353cf4b8f67ed 100644 (file)
--- a/trace.c
+++ b/trace.c
@@ -51,19 +51,36 @@ int nfvasprintf(char **str, const char *fmt, va_list va)
 }
 
 /* Get a trace file descriptor from GIT_TRACE env variable. */
-static int get_trace_fd()
+static int get_trace_fd(int *need_close)
 {
        char *trace = getenv("GIT_TRACE");
 
-       if (!trace || !strcmp(trace, "0") || !strcasecmp(trace," false"))
+       if (!trace || !strcmp(trace, "") ||
+           !strcmp(trace, "0") || !strcasecmp(trace, "false"))
                return 0;
        if (!strcmp(trace, "1") || !strcasecmp(trace, "true"))
                return STDERR_FILENO;
        if (strlen(trace) == 1 && isdigit(*trace))
                return atoi(trace);
+       if (*trace == '/') {
+               int fd = open(trace, O_WRONLY | O_APPEND | O_CREAT, 0666);
+               if (fd == -1) {
+                       fprintf(stderr,
+                               "Could not open '%s' for tracing: %s\n"
+                               "Defaulting to tracing on stderr...\n",
+                               trace, strerror(errno));
+                       return STDERR_FILENO;
+               }
+               *need_close = 1;
+               return fd;
+       }
 
        fprintf(stderr, "What does '%s' for GIT_TRACE means ?\n", trace);
+       fprintf(stderr, "If you want to trace into a file, "
+               "then please set GIT_TRACE to an absolute pathname "
+               "(starting with /).\n");
        fprintf(stderr, "Defaulting to tracing on stderr...\n");
+
        return STDERR_FILENO;
 }
 
@@ -74,7 +91,8 @@ void trace_printf(const char *format, ...)
 {
        char *trace_str;
        va_list rest;
-       int fd = get_trace_fd();
+       int need_close = 0;
+       int fd = get_trace_fd(&need_close);
 
        if (!fd)
                return;
@@ -83,9 +101,12 @@ void trace_printf(const char *format, ...)
        nfvasprintf(&trace_str, format, rest);
        va_end(rest);
 
-       write_or_whine(fd, trace_str, strlen(trace_str), err_msg);
+       write_or_whine_pipe(fd, trace_str, strlen(trace_str), err_msg);
 
        free(trace_str);
+
+       if (need_close)
+               close(fd);
 }
 
 void trace_argv_printf(const char **argv, int count, const char *format, ...)
@@ -93,7 +114,8 @@ void trace_argv_printf(const char **argv, int count, const char *format, ...)
        char *argv_str, *format_str, *trace_str;
        size_t argv_len, format_len, trace_len;
        va_list rest;
-       int fd = get_trace_fd();
+       int need_close = 0;
+       int fd = get_trace_fd(&need_close);
 
        if (!fd)
                return;
@@ -117,9 +139,12 @@ void trace_argv_printf(const char **argv, int count, const char *format, ...)
        strncpy(trace_str + format_len, argv_str, argv_len);
        strcpy(trace_str + trace_len - 1, "\n");
 
-       write_or_whine(fd, trace_str, trace_len, err_msg);
+       write_or_whine_pipe(fd, trace_str, trace_len, err_msg);
 
        free(argv_str);
        free(format_str);
        free(trace_str);
+
+       if (need_close)
+               close(fd);
 }