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putty-source/windows/winpgntc.c
Simon Tatham 0112936ef7 Replace assert(false) with an unreachable() macro.
Taking a leaf out of the LLVM code base: this macro still includes an
assert(false) so that the message will show up in a typical build, but
it follows it up with a call to a function explicitly marked as no-
return.

So this ought to do a better job of convincing compilers that once a
code path hits this function it _really doesn't_ have to still faff
about with making up a bogus return value or filling in a variable
that 'might be used uninitialised' in the following code that won't be
reached anyway.

I've gone through the existing code looking for the assert(false) /
assert(0) idiom and replaced all the ones I found with the new macro,
which also meant I could remove a few pointless return statements and
variable initialisations that I'd already had to put in to placate
compiler front ends.
2019-01-03 08:12:28 +00:00

127 lines
3.4 KiB
C

/*
* Pageant client code.
*/
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include "putty.h"
#include "pageant.h" /* for AGENT_MAX_MSGLEN */
#ifndef NO_SECURITY
#include "winsecur.h"
#endif
#define AGENT_COPYDATA_ID 0x804e50ba /* random goop */
bool agent_exists(void)
{
HWND hwnd;
hwnd = FindWindow("Pageant", "Pageant");
if (!hwnd)
return false;
else
return true;
}
void agent_cancel_query(agent_pending_query *q)
{
unreachable("Windows agent queries are never asynchronous!");
}
agent_pending_query *agent_query(
strbuf *query, void **out, int *outlen,
void (*callback)(void *, void *, int), void *callback_ctx)
{
HWND hwnd;
char *mapname;
HANDLE filemap;
unsigned char *p, *ret;
int id, retlen;
COPYDATASTRUCT cds;
SECURITY_ATTRIBUTES sa, *psa;
PSECURITY_DESCRIPTOR psd = NULL;
PSID usersid = NULL;
*out = NULL;
*outlen = 0;
if (query->len > AGENT_MAX_MSGLEN)
return NULL; /* query too large */
hwnd = FindWindow("Pageant", "Pageant");
if (!hwnd)
return NULL; /* *out == NULL, so failure */
mapname = dupprintf("PageantRequest%08x", (unsigned)GetCurrentThreadId());
psa = NULL;
#ifndef NO_SECURITY
if (got_advapi()) {
/*
* Make the file mapping we create for communication with
* Pageant owned by the user SID rather than the default. This
* should make communication between processes with slightly
* different contexts more reliable: in particular, command
* prompts launched as administrator should still be able to
* run PSFTPs which refer back to the owning user's
* unprivileged Pageant.
*/
usersid = get_user_sid();
if (usersid) {
psd = (PSECURITY_DESCRIPTOR)
LocalAlloc(LPTR, SECURITY_DESCRIPTOR_MIN_LENGTH);
if (psd) {
if (p_InitializeSecurityDescriptor
(psd, SECURITY_DESCRIPTOR_REVISION) &&
p_SetSecurityDescriptorOwner(psd, usersid, false)) {
sa.nLength = sizeof(sa);
sa.bInheritHandle = true;
sa.lpSecurityDescriptor = psd;
psa = &sa;
} else {
LocalFree(psd);
psd = NULL;
}
}
}
}
#endif /* NO_SECURITY */
filemap = CreateFileMapping(INVALID_HANDLE_VALUE, psa, PAGE_READWRITE,
0, AGENT_MAX_MSGLEN, mapname);
if (filemap == NULL || filemap == INVALID_HANDLE_VALUE) {
sfree(mapname);
return NULL; /* *out == NULL, so failure */
}
p = MapViewOfFile(filemap, FILE_MAP_WRITE, 0, 0, 0);
strbuf_finalise_agent_query(query);
memcpy(p, query->s, query->len);
cds.dwData = AGENT_COPYDATA_ID;
cds.cbData = 1 + strlen(mapname);
cds.lpData = mapname;
/*
* The user either passed a null callback (indicating that the
* query is required to be synchronous) or CreateThread failed.
* Either way, we need a synchronous request.
*/
id = SendMessage(hwnd, WM_COPYDATA, (WPARAM) NULL, (LPARAM) &cds);
if (id > 0) {
retlen = 4 + GET_32BIT(p);
ret = snewn(retlen, unsigned char);
if (ret) {
memcpy(ret, p, retlen);
*out = ret;
*outlen = retlen;
}
}
UnmapViewOfFile(p);
CloseHandle(filemap);
sfree(mapname);
if (psd)
LocalFree(psd);
return NULL;
}