Document error-related functions.

git-svn-id: http://lm-sensors.org/svn/lm-sensors/trunk@5654 7894878c-1315-0410-8ee3-d5d059ff63e0

lib/libsensors.3

@@ -70,6 +70,17 @@ libsensors \- publicly accessible functions provided by the sensors library
 .BI "int sensors_set_value(const sensors_chip_name *" name ", int " subfeat_nr ","
 .BI "                      double " value ");"
 .BI "int sensors_do_chip_sets(const sensors_chip_name *" name ");"
+
+.B #include <sensors/error.h>
+
+/* Error decoding */
+.BI "const char *sensors_strerror(int " errnum ");"
+
+/* Error handlers */
+.BI "void (*sensors_parse_error) (const char *" err ", int " lineno ");"
+.BI "void (*sensors_parse_error_wfn) (const char *" err ","
+.BI "                                 const char *" filename ", int " lineno ");"
+.BI "void (*sensors_fatal_error) (const char *" proc ", const char *" err ");"
 .fi
 
 .SH DESCRIPTION
@@ -148,6 +159,34 @@ failure.
 executes all set statements for this particular chip. The chip may contain
 wildcards!  This function will return 0 on success, and <0 on failure.
 
+.B sensors_strerror()
+returns a pointer to a string which describes the error.
+errnum may be negative (the corresponding positive error is returned).
+You may not modify the result!
+
+.B sensors_parse_error()
+and
+.B sensors_parse_error_wfn()
+are functions which are called when a parse error is detected. Give them
+new values, and your own functions are called instead of the default (which
+print to stderr). These functions may terminate the program, but they
+usually output an error and return. The first function is the original
+one, the second one was added later when support for multiple
+configuration files was added.
+The library code now only calls the second function. However, for
+backwards compatibility, if an application provides a custom handling
+function for the first function but not the second, then all parse
+errors will be reported using the first function (that is, the filename
+is never reported.)
+Note that filename can be NULL (if filename isn't known) and lineno
+can be 0 (if the error occurs before the actual parsing starts.)
+
+.B sensors_fatal_error()
+Is a function which is called when an immediately fatal error (like no
+memory left) is detected. Give it a new value, and your own function
+is called instead of the default (which prints to stderr and ends
+the program). Never let it return!
+
 .SH DATA STRUCTURES
 
 Structure \fBsensors_feature\fR contains information related to a given