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putty-source/windows/utils/win_strerror.c
Simon Tatham 3396c97da9 New library-style 'utils' subdirectories.
Now that the new CMake build system is encouraging us to lay out the
code like a set of libraries, it seems like a good idea to make them
look more _like_ libraries, by putting things into separate modules as
far as possible.

This fixes several previous annoyances in which you had to link
against some object in order to get a function you needed, but that
object also contained other functions you didn't need which included
link-time symbol references you didn't want to have to deal with. The
usual offender was subsidiary supporting programs including misc.c for
some innocuous function and then finding they had to deal with the
requirements of buildinfo().

This big reorganisation introduces three new subdirectories called
'utils', one at the top level and one in each platform subdir. In each
case, the directory contains basically the same files that were
previously placed in the 'utils' build-time library, except that the
ones that were extremely miscellaneous (misc.c, utils.c, uxmisc.c,
winmisc.c, winmiscs.c, winutils.c) have been split up into much
smaller pieces.
2021-04-18 08:18:27 +01:00

73 lines
2.1 KiB
C

/*
* Wrapper around the Windows FormatMessage system for retrieving the
* text of a system error code, with a simple API similar to strerror.
*
* Works by keeping a tree234 containing mappings from system error
* codes to strings. Entries allocated in this tree are simply never
* freed.
*
* Also, the returned string has its trailing newline removed (so it
* can go in places like the Event Log that never want a newline), and
* is prefixed with the error number (so that if a user sends an error
* report containing a translated error message we can't read, we can
* still find out what the error actually was).
*/
#include "putty.h"
struct errstring {
int error;
char *text;
};
static int errstring_find(void *av, void *bv)
{
int *a = (int *)av;
struct errstring *b = (struct errstring *)bv;
if (*a < b->error)
return -1;
if (*a > b->error)
return +1;
return 0;
}
static int errstring_compare(void *av, void *bv)
{
struct errstring *a = (struct errstring *)av;
return errstring_find(&a->error, bv);
}
static tree234 *errstrings = NULL;
const char *win_strerror(int error)
{
struct errstring *es;
if (!errstrings)
errstrings = newtree234(errstring_compare);
es = find234(errstrings, &error, errstring_find);
if (!es) {
char msgtext[65536]; /* maximum size for FormatMessage is 64K */
es = snew(struct errstring);
es->error = error;
if (!FormatMessage((FORMAT_MESSAGE_FROM_SYSTEM |
FORMAT_MESSAGE_IGNORE_INSERTS), NULL, error,
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
msgtext, lenof(msgtext)-1, NULL)) {
sprintf(msgtext,
"(unable to format: FormatMessage returned %u)",
(unsigned int)GetLastError());
} else {
int len = strlen(msgtext);
if (len > 0 && msgtext[len-1] == '\n')
msgtext[len-1] = '\0';
}
es->text = dupprintf("Error %d: %s", error, msgtext);
add234(errstrings, es);
}
return es->text;
}