kc3-lang/libxkbcommon

diff --git a/Makefile.am b/Makefile.am
index ca715fe..02c0f57 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -75,7 +75,6 @@ libxkbcommon_la_SOURCES = \
 	src/state.c \
 	src/text.c \
 	src/text.h \
-	src/utils.c \
 	src/utils.h \
 	src/xkb-priv.h
 
diff --git a/src/context.c b/src/context.c
index a0bb9a9..18a8222 100644
--- a/src/context.c
+++ b/src/context.c
@@ -25,8 +25,12 @@
 
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <ctype.h>
+#include <errno.h>
+#include <stdarg.h>
 #include <stdio.h>
 #include <unistd.h>
+#include <syslog.h>
 
 #include "xkb-priv.h"
 #include "atom.h"
@@ -34,6 +38,12 @@
 struct xkb_context {
     int refcnt;
 
+    ATTR_PRINTF(3, 0) void (*log_fn)(struct xkb_context *ctx, int priority,
+                                     const char *fmt, va_list args);
+    int log_priority;
+    int log_verbosity;
+    void *user_data;
+
     darray(char *) includes;
 
     /* xkbcomp needs to assign sequential IDs to XkbFile's it creates. */
@@ -175,18 +185,97 @@ xkb_context_unref(struct xkb_context *ctx)
     free(ctx);
 }
 
+static const char *
+priority_to_prefix(int priority)
+{
+    switch (priority) {
+    case LOG_DEBUG:
+        return "Debug:";
+    case LOG_INFO:
+        return "Info:";
+    case LOG_WARNING:
+        return "Warning:";
+    case LOG_ERR:
+        return "Error:";
+    case LOG_CRIT:
+    case LOG_ALERT:
+    case LOG_EMERG:
+        return "Internal error:";
+    default:
+        return "";
+    }
+}
+
+ATTR_PRINTF(3, 0) static void
+default_log_fn(struct xkb_context *ctx, int priority,
+               const char *fmt, va_list args)
+{
+    const char *prefix = priority_to_prefix(priority);
+
+    if (prefix)
+        fprintf(stderr, "%-15s", prefix);
+    vfprintf(stderr, fmt, args);
+}
+
+static int
+log_priority(const char *priority) {
+    char *endptr;
+    int prio;
+
+    errno = 0;
+    prio = strtol(priority, &endptr, 10);
+    if (errno == 0 && (endptr[0] == '\0' || isspace(endptr[0])))
+        return prio;
+    if (strncasecmp(priority, "err", 3) == 0)
+        return LOG_ERR;
+    if (strncasecmp(priority, "warn", 4) == 0)
+        return LOG_WARNING;
+    if (strncasecmp(priority, "info", 4) == 0)
+        return LOG_INFO;
+    if (strncasecmp(priority, "debug", 5) == 0)
+        return LOG_DEBUG;
+
+    return LOG_ERR;
+}
+
+static int
+log_verbosity(const char *verbosity) {
+    char *endptr;
+    int v;
+
+    errno = 0;
+    v = strtol(verbosity, &endptr, 10);
+    if (errno == 0)
+        return v;
+
+    return 0;
+}
+
 /**
  * Create a new context.
  */
 XKB_EXPORT struct xkb_context *
 xkb_context_new(enum xkb_context_flags flags)
 {
+    const char *env;
     struct xkb_context *ctx = calloc(1, sizeof(*ctx));
 
     if (!ctx)
         return NULL;
 
     ctx->refcnt = 1;
+    ctx->log_fn = default_log_fn;
+    ctx->log_priority = LOG_ERR;
+    ctx->log_verbosity = 0;
+
+    /* Environment overwrites defaults. */
+    env = getenv("XKB_LOG");
+    if (env)
+        xkb_set_log_priority(ctx, log_priority(env));
+
+    env = getenv("XKB_VERBOSITY");
+    if (env)
+        xkb_set_log_verbosity(ctx, log_verbosity(env));
 
     if (!(flags & XKB_CONTEXT_NO_DEFAULT_INCLUDES) &&
         !xkb_context_include_path_append_default(ctx)) {
@@ -220,3 +309,63 @@ xkb_atom_text(struct xkb_context *ctx, xkb_atom_t atom)
 {
     return atom_text(ctx->atom_table, atom);
 }
+
+void
+xkb_log(struct xkb_context *ctx, int priority, const char *fmt, ...)
+{
+    va_list args;
+
+    va_start(args, fmt);
+    /* NOTE: This test will be removed in a few commits. */
+    if (ctx)
+        ctx->log_fn(ctx, priority, fmt, args);
+    else
+        default_log_fn(ctx, priority, fmt, args);
+    va_end(args);
+}
+
+XKB_EXPORT void
+xkb_set_log_fn(struct xkb_context *ctx,
+               void (*log_fn)(struct xkb_context *ctx, int priority,
+                              const char *fmt, va_list args))
+{
+    ctx->log_fn = log_fn;
+}
+
+XKB_EXPORT int
+xkb_get_log_priority(struct xkb_context *ctx)
+{
+    return ctx->log_priority;
+}
+
+XKB_EXPORT void
+xkb_set_log_priority(struct xkb_context *ctx, int priority)
+{
+    ctx->log_priority = priority;
+}
+
+XKB_EXPORT int
+xkb_get_log_verbosity(struct xkb_context *ctx)
+{
+    return ctx->log_verbosity;
+}
+
+XKB_EXPORT void
+xkb_set_log_verbosity(struct xkb_context *ctx, int verbosity)
+{
+    ctx->log_verbosity = verbosity;
+}
+
+XKB_EXPORT void *
+xkb_get_user_data(struct xkb_context *ctx)
+{
+    if (ctx)
+        return ctx->user_data;
+    return NULL;
+}
+
+XKB_EXPORT void
+xkb_set_user_data(struct xkb_context *ctx, void *user_data)
+{
+    ctx->user_data = user_data;
+}
diff --git a/src/utils.c b/src/utils.c
deleted file mode 100644
index d1f79bb..0000000
--- a/src/utils.c
+++ /dev/null
@@ -1,154 +0,0 @@
-/*\
- *
- *                          COPYRIGHT 1990
- *                    DIGITAL EQUIPMENT CORPORATION
- *                       MAYNARD, MASSACHUSETTS
- *                        ALL RIGHTS RESERVED.
- *
- * THE INFORMATION IN THIS SOFTWARE IS SUBJECT TO CHANGE WITHOUT NOTICE AND
- * SHOULD NOT BE CONSTRUED AS A COMMITMENT BY DIGITAL EQUIPMENT CORPORATION.
- * DIGITAL MAKES NO REPRESENTATIONS ABOUT THE SUITABILITY OF THIS SOFTWARE
- * FOR ANY PURPOSE.  IT IS SUPPLIED "AS IS" WITHOUT EXPRESS OR IMPLIED
- * WARRANTY.
- *
- * IF THE SOFTWARE IS MODIFIED IN A MANNER CREATING DERIVATIVE COPYRIGHT
- * RIGHTS, APPROPRIATE LEGENDS MAY BE PLACED ON THE DERIVATIVE WORK IN
- * ADDITION TO THAT SET FORTH ABOVE.
- *
- * Permission to use, copy, modify, and distribute this software and its
- * documentation for any purpose and without fee is hereby granted, provided
- * that the above copyright notice appear in all copies and that both that
- * copyright notice and this permission notice appear in supporting
- * documentation, and that the name of Digital Equipment Corporation not be
- * used in advertising or publicity pertaining to distribution of the
- * software without specific, written prior permission.
- \*/
-
-#include <ctype.h>
-#include <stdlib.h>
-#include <stdarg.h>
-#include <string.h>
-
-#include "utils.h"
-
-static FILE *errorFile = NULL;
-static int outCount = 0;
-static char *preMsg = NULL;
-static char *prefix = NULL;
-
-bool
-uSetErrorFile(char *name)
-{
-    if ((errorFile != NULL) && (errorFile != stderr)) {
-        fprintf(errorFile, "switching to %s\n", name ? name : "stderr");
-        fclose(errorFile);
-    }
-    if (name != NULL)
-        errorFile = fopen(name, "w");
-    else
-        errorFile = stderr;
-    if (errorFile == NULL) {
-        errorFile = stderr;
-        return false;
-    }
-    return true;
-}
-
-void
-uInformation(const char *s, ...)
-{
-    va_list args;
-
-    if (!errorFile)
-        errorFile = stderr;
-
-    va_start(args, s);
-    vfprintf(errorFile, s, args);
-    va_end(args);
-    fflush(errorFile);
-}
-
-/***====================================================================***/
-
-void
-uAction(const char *s, ...)
-{
-    va_list args;
-
-    if (!errorFile)
-        errorFile = stderr;
-
-    if (prefix != NULL)
-        fprintf(errorFile, "%s", prefix);
-    fprintf(errorFile, "                  ");
-    va_start(args, s);
-    vfprintf(errorFile, s, args);
-    va_end(args);
-    fflush(errorFile);
-}
-
-/***====================================================================***/
-
-void
-uWarning(const char *s, ...)
-{
-    va_list args;
-
-    if (!errorFile)
-        errorFile = stderr;
-
-    if ((outCount == 0) && (preMsg != NULL))
-        fprintf(errorFile, "%s\n", preMsg);
-    if (prefix != NULL)
-        fprintf(errorFile, "%s", prefix);
-    fprintf(errorFile, "Warning:          ");
-    va_start(args, s);
-    vfprintf(errorFile, s, args);
-    va_end(args);
-    fflush(errorFile);
-    outCount++;
-}
-
-/***====================================================================***/
-
-void
-uError(const char *s, ...)
-{
-    va_list args;
-
-    if (!errorFile)
-        errorFile = stderr;
-
-    if ((outCount == 0) && (preMsg != NULL))
-        fprintf(errorFile, "%s\n", preMsg);
-    if (prefix != NULL)
-        fprintf(errorFile, "%s", prefix);
-    fprintf(errorFile, "Error:            ");
-    va_start(args, s);
-    vfprintf(errorFile, s, args);
-    va_end(args);
-    fflush(errorFile);
-    outCount++;
-}
-
-/***====================================================================***/
-
-void
-uInternalError(const char *s, ...)
-{
-    va_list args;
-
-    if (!errorFile)
-        errorFile = stderr;
-
-    if ((outCount == 0) && (preMsg != NULL))
-        fprintf(errorFile, "%s\n", preMsg);
-    if (prefix != NULL)
-        fprintf(errorFile, "%s", prefix);
-    fprintf(errorFile, "Internal error:   ");
-    va_start(args, s);
-    vfprintf(errorFile, s, args);
-    va_end(args);
-    fflush(errorFile);
-    outCount++;
-}
diff --git a/src/utils.h b/src/utils.h
index 4ea703a..7d4e612 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -29,10 +29,6 @@
 
 /***====================================================================***/
 
-#include <stdbool.h>
-#include <stdio.h>
-#include <stdlib.h>
-
 /*
  * We sometimes malloc strings and then expose them as const char*'s. This
  * macro is used when we free these strings in order to avoid -Wcast-qual
@@ -73,33 +69,10 @@
 #define ATTR_MALLOC
 #endif
 
-extern bool
-uSetErrorFile(char *name);
-
-#define INFO uInformation
-
-ATTR_PRINTF(1, 2) void
-uInformation(const char *s, ...);
-
-#define ACTION uAction
-
-ATTR_PRINTF(1, 2) void
-uAction(const char *s, ...);
-
-#define WARN uWarning
-
-ATTR_PRINTF(1, 2) void
-uWarning(const char *s, ...);
-
-#define ERROR uError
-
-ATTR_PRINTF(1, 2) void
-uError(const char *s, ...);
-
-/* WSGO stands for "Weird Stuff Going On" (wtf???) */
-#define WSGO uInternalError
-
-ATTR_PRINTF(1, 2) void
-uInternalError(const char *s, ...);
+#define INFO(...) xkb_log(NULL, LOG_INFO, __VA_ARGS__)
+#define WARN(...) xkb_log(NULL, LOG_WARNING, __VA_ARGS__)
+#define ERROR(...) xkb_log(NULL, LOG_ERR, __VA_ARGS__)
+#define WSGO(...) xkb_log(NULL, LOG_CRIT, __VA_ARGS__)
+#define ACTION(...) xkb_log(NULL, -1, __VA_ARGS__)
 
 #endif /* UTILS_H */
diff --git a/src/xkb-priv.h b/src/xkb-priv.h
index 55a89f2..d1b135d 100644
--- a/src/xkb-priv.h
+++ b/src/xkb-priv.h
@@ -82,6 +82,7 @@
 #include <stdbool.h>
 #include <string.h>
 #include <strings.h>
+#include <syslog.h>
 #include <X11/extensions/XKB.h>
 #include <X11/X.h>
 
@@ -518,4 +519,33 @@ xkb_keysym_is_upper(xkb_keysym_t keysym);
 bool
 xkb_keysym_is_keypad(xkb_keysym_t keysym);
 
+ATTR_PRINTF(3, 4) void
+xkb_log(struct xkb_context *ctx, int priority, const char *fmt, ...);
+
+#define xkb_log_cond(ctx, prio, ...) \
+    do { \
+        if (xkb_get_log_priority(ctx) >= (prio)) \
+            xkb_log((ctx), (prio), __VA_ARGS__); \
+    } while (0)
+
+#define xkb_log_cond_lvl(ctx, prio, lvl, ...) \
+    do { \
+        if (xkb_get_log_verbosity(ctx) >= (lvl)) \
+            xkb_log_cond((ctx), (prio), __VA_ARGS__); \
+    } while (0)
+
+/*
+ * The format is not part of the argument list in order to avoid the
+ * "ISO C99 requires rest arguments to be used" warning when only the
+ * format is supplied without arguments. Not supplying it would still
+ * result in an error, though.
+ */
+#define log_dbg(ctx, ...) xkb_log_cond((ctx), LOG_DEBUG, __VA_ARGS__)
+#define log_info(ctx, ...) xkb_log_cond((ctx), LOG_INFO, __VA_ARGS__)
+#define log_warn(ctx, ...) xkb_log_cond((ctx), LOG_WARNING, __VA_ARGS__)
+#define log_err(ctx, ...) xkb_log_cond((ctx), LOG_ERR, __VA_ARGS__)
+#define log_wsgo(ctx, ...) xkb_log_cond((ctx), LOG_CRIT, __VA_ARGS__)
+#define log_lvl(ctx, lvl, ...) \
+    xkb_log_cond_lvl((ctx), LOG_WARNING, (lvl), __VA_ARGS__)
+
 #endif /* XKB_PRIV_H */
diff --git a/xkbcommon/xkbcommon.h b/xkbcommon/xkbcommon.h
index 42f70ad..8c772ae 100644
--- a/xkbcommon/xkbcommon.h
+++ b/xkbcommon/xkbcommon.h
@@ -249,6 +249,77 @@ xkb_context_unref(struct xkb_context *context);
 /** @} */
 
 /**
+ * @defgroup logging Logging handling
+ * These functions allow you to manipulate how logging from this library
+ * will be handled.
+ *
+ * @{
+ */
+
+/**
+ * Sets the function to be called for logging messages, instead of the
+ * default logger which writes to stderr.
+ **/
+void
+xkb_set_log_fn(struct xkb_context *context,
+               void (*log_fn)(struct xkb_context *context, int priority,
+                              const char *format, va_list args));
+/**
+ * Sets the current logging priority. The value controls which messages
+ * are logged.
+ *
+ * The value should be one of LOG_ERR, LOG_WARNING, LOG_DEBUG, etc., see
+ * syslog(3) or syslog.h.  The default priority is LOG_ERR.
+ * The environment variable XKB_LOG, if set, overrides the default value
+ * and may be specified as a priority number or name.
+ */
+void
+xkb_set_log_priority(struct xkb_context *context, int priority);
+
+/**
+ * Returns the current logging priority.
+ */
+int
+xkb_get_log_priority(struct xkb_context *context);
+
+/**
+ * Sets the current logging verbosity, a value from 0 to 10.
+ *
+ * The library can generate a number of warnings which are not helpful to
+ * ordinary users of the library.  The verbosity may be increased if more
+ * information is desired (e.g. when developing a keymap).  Defaults to 0.
+ * The environment variable XKB_VERBOSITY, if set, overrdies the default
+ * value.
+ *
+ * Note that most verbose messages are of priority LOG_WARNING or lower.
+ */
+void
+xkb_set_log_verbosity(struct xkb_context *ctx, int verbosity);
+
+/**
+ * Returns the current logging verbosity.
+ */
+int
+xkb_get_log_verbosity(struct xkb_context *ctx);
+
+/**
+ * Retrieves stored data pointer from the context.  This might be useful
+ * to access from callbacks like a custom logging function.
+ *
+ * If context is NULL, returns NULL.
+ **/
+void *
+xkb_get_user_data(struct xkb_context *context);
+
+/**
+ * Store custom user data in the context.
+ */
+void
+xkb_set_user_data(struct xkb_context *context, void *user_data);
+
+/** @} */
+
+/**
  * @defgroup map Keymap management
  * These utility functions allow you to create and deallocate XKB keymaps.
  *