add error.h

Signed-off-by: Mattias Andrée <maandree@operamail.com>

1 files changed, 188 insertions, 0 deletions

diff --git a/src/error.c b/src/error.c
new file mode 100644
index 0000000..ee39ccf
--- /dev/null
+++ b/src/error.c
@@ -0,0 +1,188 @@
+/**
+ * slibc — Yet another C library
+ * Copyright © 2015  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <error.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <errno.h>
+
+
+
+/**
+ * Print an error message with a detailed description, and optionally exit.
+ * 
+ * This is a GNU extension.
+ * 
+ * @param  status  The process will exit, with the function returning, with this
+ *                 exit status, unless it is zero. If zero, the process shall not exit.
+ * @param  errnum  The value of `errno` when the error occurred, zero if the a textual
+ *                 description of the error, further than that of `format`, shall not
+ *                 be printed.
+ * @param  format  Formatting-string for a detailed description of what happend.
+ * @param  args    Formatting-arguments for `format`.
+ */
+void error(int status, int errnum, const char* format, ...)
+{
+  va_list args;
+  va_start(args, format);
+  verror_at_line(status, errnum, NULL, 0, format, args);
+  va_end(args);
+}
+
+
+/**
+ * Variant of `error` that uses `va_list` instead of variadic arguments.
+ * 
+ * This is a slibc extension to the GNU extension `error`.
+ * 
+ * @param  status  The process will exit, with the function returning, with this
+ *                 exit status, unless it is zero. If zero, the process shall not exit.
+ * @param  errnum  The value of `errno` when the error occurred, zero if the a textual
+ *                 description of the error, further than that of `format`, shall not
+ *                 be printed.
+ * @param  format  Formatting-string for a detailed description of what happend.
+ * @param  args    Formatting-arguments for `format`.
+ */
+void verror(int status, int errnum, const char* format, va_list args)
+{
+  verror_at_line(status, errnum, NULL, 0, format, args);
+}
+
+
+/**
+ * Variant of `error` that prints the filename and the line
+ * number whence the error occurred.
+ * 
+ * This is a GNU extension.
+ * 
+ * @param  status    The process will exit, with the function returning, with this
+ *                   exit status, unless it is zero. If zero, the process shall not exit.
+ * @param  errnum    The value of `errno` when the error occurred, zero if the a textual
+ *                   description of the error, further than that of `format`, shall not
+ *                   be printed.
+ * @param  filename  The filename of the source code file where the error occurred.
+ * @param  linenum   The line number of in the source code file where the error occurred.
+ * @param  format    Formatting-string for a detailed description of what happend.
+ * @param  args      Formatting-arguments for `format`.
+ */
+void error_at_line(int status, int errnum, const char* filename,
+		   unsigned int linenum, const char* format, ...)
+{
+  va_list args;
+  va_start(args, format);
+  verror_at_line(status, errnu, filename, linenum, format, args);
+  va_end(args);
+}
+
+
+/**
+ * Variant of `verror` that prints the filename and the line
+ * number whence the error occurred.
+ * 
+ * This is a slibc extension to the GNU extension `error_at_line`.
+ * 
+ * @param  status    The process will exit, with the function returning, with this
+ *                   exit status, unless it is zero. If zero, the process shall not exit.
+ * @param  errnum    The value of `errno` when the error occurred, zero if the a textual
+ *                   description of the error, further than that of `format`, shall not
+ *                   be printed.
+ * @param  filename  The filename of the source code file where the error occurred.
+ * @param  linenum   The line number of in the source code file where the error occurred.
+ * @param  format    Formatting-string for a detailed description of what happend.
+ * @param  args      Formatting-arguments for `format`.
+ */
+void verror_at_line(int status, int errnum, const char* filename,
+		    unsigned int linenum, const char* format, va_list args)
+{
+  int tty = isatty(STDERR_FILENO);
+  void (*pname)(void) = error_print_progname;
+  
+  static const char* last_filename = NULL;
+  static unsigned int last_linenum = 0;
+  static int last_errnum = 0;
+  
+  if (error_one_per_line)
+    if ((last_filename == filename) && (last_linenum == linenum) && (last_errnum == errnum))
+      goto skip_print;
+  
+  if (pname != NULL)
+    pname();
+  else
+    {
+      fflush(stdout);
+      fprintf(stderr, "%(\033[0;1;31m)%s%(\033[0m)",
+	      tty, program_invocation_name, tty);
+    }
+  
+  fprintf(stderr, "%(: %(\033[35m%)%s%(\033[0m%): %(\033[32m%)%u%(\033[0m%)%)%(: %s%)%(: %)",
+	  filename != NULL, tty, filename, tty, tty, filenum, tty,
+	  errnum != 0, strerror(errnum) /* TODO strerror is not MT-Safe */, format != NULL);
+  
+  if (filename != NULL)
+    last_filename = filename, last_linenum = linenum, last_errnum = errnum;
+  
+  vfprintf(stderr, format, args);
+  fprintf(stderr, "\n", program_invocation_name);
+  fflush(stderr);
+  
+ skip_print:
+  error_message_count++; /* TODO lock around this */
+  if (status)
+    exit(status);
+}
+
+
+/**
+ * Counts the number of times `error` ( verror`) and
+ * `error_at_line` (`verror_at_line`) has returned.
+ * This variable is global and shared by all threads.
+ * 
+ * This is a GNU extension.
+ */
+volatile unsigned int error_message_count = 0;
+
+
+/**
+ * If set to non-zero (the default), `error_at_line`
+ * and `verror_at_line` restrict themself to only
+ * print an error the first time it appears. This
+ * is determined by the uniqueness of the combination
+ * of the values on `filename` and `linenum`. However
+ * it will forget the line the next time the function
+ * is called from a different line. This variable is
+ * global and shared by all threads. Has a slibc
+ * modification, `errnum` is also remembered, meaning
+ * if the error code is different (zero is considered
+ * an error code), the error is printed even if it
+ * occurred on the same line as the last time.
+ * 
+ * This is a GNU extension.
+ */
+volatile int error_one_per_line = 1;
+
+
+/**
+ * If not `NULL`, this function is used instead of
+ * flushing stdout and printing the process name to
+ * stderr, by `error` (`verror`) and `verror_at_line`
+ * (`verror_at_line`). This variable is global and
+ * shared by all threads.
+ * 
+ * This is a GNU extension.
+ */
+volatile void (*error_print_progname)(void) = NULL;
+