Simplify configuration dumping

Prior to this change, there was a lot of duplicated code within the dump
routines, which would call out to a common `print_section` routine that
had global state. This causes problems from a multi-threaded perspective
in that multiple calls to `x52d_config_save_file` were not MT-safe.

In addition, the dump logic was written such that it could only be used
in the config dump. It is desired that we add functionality to return
the formatted config value as a string in a different part of the code
as well.

This change brings in the shared state into a stack variable, and
changes the dump functions to return a const char *, thereby allowing
for greater reuse, as well as getting rid of the shared state. However,
there is still a little bit of shared state in the `int_dumper` routine.
This can be ignored for now, but we should possibly figure out how to
get rid of the shared state altogether.

daemon/x52d_config_dump.c

@@ -19,106 +19,74 @@
 #include "x52d_config.h"
 #include "x52d_const.h"
 
-static char *current_section = NULL;
-
-// Print the current section to the file
-static void print_section(FILE *cfg, const char *section)
-{
-    if (current_section == NULL || strcasecmp(current_section, section)) {
-        if (current_section != NULL) {
-            free(current_section);
-        }
-
-        current_section = strdup(section);
-        PINELOG_TRACE("Printing section header %s", section);
-
-        fprintf(cfg, "[%s]\n", section);
-    }
-}
-
 // Create a pointer "name" of type "type", which stores the value of the
 // corresponding element within the config struct.
 #define CONFIG_PTR(type, name) type name = (type)((uintptr_t)cfg + offset)
 
 // Check if the parameters are all valid
-#define CHECK_PARAMS() do { if (cfg == NULL || section == NULL || key == NULL) { return EINVAL; } } while(0)
+#define CHECK_PARAMS() do { if (cfg == NULL || section == NULL || key == NULL) { return NULL; } } while(0)
 
-static int bool_dumper(FILE *file, const char *section, const char *key, const struct x52d_config *cfg, size_t offset)
+static const char * bool_dumper(const char *section, const char *key, const struct x52d_config *cfg, size_t offset)
 {
     CONFIG_PTR(bool *, config);
     CHECK_PARAMS();
 
-    print_section(file, section);
     PINELOG_TRACE("Printing bool value %s.%s from offset %lu value = %d",
                   section, key, offset, *config);
-    fprintf(file, "%s = %s\n", key, *config ? "true" : "false");
+    return *config ? "true" : "false";
-
-    return 0;
 }
 
-static int string_dumper(FILE *file, const char *section, const char *key, struct x52d_config *cfg, size_t offset)
+static const char * string_dumper(const char *section, const char *key, struct x52d_config *cfg, size_t offset)
 {
     CONFIG_PTR(char *, config);
     CHECK_PARAMS();
 
-    print_section(file, section);
     PINELOG_TRACE("Printing string value %s.%s from offset %lu value = %s",
                   section, key, offset, config);
-    fprintf(file, "%s = %s\n", key, config);
+    return config;
-
-    return 0;
 }
 
-static int int_dumper(FILE *file, const char *section, const char *key, struct x52d_config *cfg, size_t offset)
+static const char * int_dumper(const char *section, const char *key, struct x52d_config *cfg, size_t offset)
 {
+    static char dump[256];
     CONFIG_PTR(int *, config);
     CHECK_PARAMS();
 
-    print_section(file, section);
     PINELOG_TRACE("Printing int value %s.%s from offset %lu value = %d",
                   section, key, offset, *config);
-    fprintf(file, "%s = %d\n", key, *config);
+    snprintf(dump, sizeof(dump), "%d", *config);
 
-    return 0;
+    return dump;
 }
 
-static int led_dumper(FILE *file, const char *section, const char *key, struct x52d_config *cfg, size_t offset)
+static const char * led_dumper(const char *section, const char *key, struct x52d_config *cfg, size_t offset)
 {
     CONFIG_PTR(libx52_led_state *, config);
     CHECK_PARAMS();
 
-    print_section(file, section);
     PINELOG_TRACE("Printing led value %s.%s from offset %lu value = %d",
                   section, key, offset, *config);
-    fprintf(file, "%s = %s\n", key, libx52_led_state_to_str(*config));
+    return libx52_led_state_to_str(*config);
-
-    return 0;
 }
 
-static int clock_format_dumper(FILE *file, const char *section, const char *key, struct x52d_config *cfg, size_t offset)
+static const char * clock_format_dumper(const char *section, const char *key, struct x52d_config *cfg, size_t offset)
 {
     CONFIG_PTR(libx52_clock_format *, config);
     CHECK_PARAMS();
 
-    print_section(file, section);
     PINELOG_TRACE("Printing clock format value %s.%s from offset %lu value = %d",
                   section, key, offset, *config);
-    fprintf(file, "%s = %s\n", key, libx52_clock_format_to_str(*config));
+    return libx52_clock_format_to_str(*config);
-
-    return 0;
 }
 
-static int date_format_dumper(FILE *file, const char *section, const char *key, struct x52d_config *cfg, size_t offset)
+static const char * date_format_dumper(const char *section, const char *key, struct x52d_config *cfg, size_t offset)
 {
     CONFIG_PTR(libx52_date_format *, config);
     CHECK_PARAMS();
 
-    print_section(file, section);
     PINELOG_TRACE("Printing date format value %s.%s from offset %lu value = %d",
                   section, key, offset, *config);
-    fprintf(file, "%s = %s\n", key, libx52_date_format_to_str(*config));
+    return libx52_date_format_to_str(*config);
-
-    return 0;
 }
 
 #undef CHECK_PARAMS
@@ -126,8 +94,10 @@ static int date_format_dumper(FILE *file, const char *section, const char *key,
 
 int x52d_config_save_file(struct x52d_config *cfg, const char *cfg_file)
 {
-    int rc;
     FILE *cfg_fp;
+    char *current_section = NULL;
+    const char *value;
+
     if (cfg == NULL || cfg_file == NULL) {
         return EINVAL;
     }
@@ -139,26 +109,36 @@ int x52d_config_save_file(struct x52d_config *cfg, const char *cfg_file)
 
     cfg_fp = fopen(cfg_file, "w");
     if (cfg_fp == NULL) {
-        rc = errno;
         PINELOG_ERROR(_("Unable to save config file %s - code %d: %s"),
-                      cfg_file, rc, strerror(rc));
+                      cfg_file, errno, strerror(errno));
-        return rc;
+        return 1;
     }
 
     PINELOG_TRACE("Saving configuration to file %s", cfg_file);
     #define CFG(section, key, name, type, def) do { \
+        if (current_section == NULL || strcasecmp(current_section, #section)) { \
+            if (current_section != NULL) { \
+                free(current_section); \
+            } \
+            current_section = strdup(#section); \
+            PINELOG_TRACE("Printing section header %s", #section); \
+            fprintf(cfg_fp, "[%s]\n", #section); \
+        } \
         PINELOG_TRACE("Dumping " #section "." #key " to file %s", cfg_file); \
-        rc = type ## _dumper(cfg_fp, #section, #key, cfg, offsetof(struct x52d_config, name)); \
+        value = type ## _dumper(#section, #key, cfg, offsetof(struct x52d_config, name)); \
-        if (rc) { \
+        if (value == NULL) { \
-            PINELOG_ERROR(_("Failed to dump %s.%s to config file %s - code %d: %s"), \
+            PINELOG_ERROR(_("Failed to dump %s.%s to config file %s"), \
-                          #section, #key, cfg_file, rc, strerror(rc)); \
+                          #section, #key, cfg_file); \
             goto exit_dump; \
+        } else { \
+            fprintf(cfg_fp, "%s = %s\n", #key, value); \
         } \
     } while (0);
     #include "x52d_config.def"
 
 exit_dump:
+    free(current_section);
     fclose(cfg_fp);
-    return rc;
+    return (value == NULL);
 }