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Clean up some code, comments and docs referring to Windows 2000 and older

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This fixes and updates a couple of comments related to outdated Windows
versions.  Particularly, src/common/exec.c had a fallback implementation
to read a file's line from a pipe because stdin/stdout/stderr does not
exist in Windows 2000 that is removed to simplify src/common/ as there
are unlikely versions of Postgres running on such platforms.

Author: Michael Paquier
Reviewed-by: Kyotaro Horiguchi, Juan José Santamaría Flecha
Discussion: https://postgr.es/m/20191219021526.GC4202@paquier.xyz
This commit is contained in:
Michael Paquier
2020-02-19 13:20:33 +09:00
parent e3ff789acf
commit e2e02191e2
6 changed files with 13 additions and 153 deletions
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132
src/common/exec.c
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@@ -354,17 +354,11 @@ find_other_exec(const char *argv0, const char *target,
/*
* The runtime library's popen() on win32 does not work when being
* called from a service when running on windows <= 2000, because
* there is no stdin/stdout/stderr.
*
* Executing a command in a pipe and reading the first line from it
* is all we need.
* Execute a command in a pipe and read the first line from it.
*/
static char *
pipe_read_line(char *cmd, char *line, int maxsize)
{
#ifndef WIN32
FILE *pgver;
/* flush output buffers in case popen does not... */
@@ -393,130 +387,6 @@ pipe_read_line(char *cmd, char *line, int maxsize)
return NULL;
return line;
#else /* WIN32 */
SECURITY_ATTRIBUTES sattr;
HANDLE childstdoutrd,
childstdoutwr,
childstdoutrddup;
PROCESS_INFORMATION pi;
STARTUPINFO si;
char *retval = NULL;
sattr.nLength = sizeof(SECURITY_ATTRIBUTES);
sattr.bInheritHandle = TRUE;
sattr.lpSecurityDescriptor = NULL;
if (!CreatePipe(&childstdoutrd, &childstdoutwr, &sattr, 0))
return NULL;
if (!DuplicateHandle(GetCurrentProcess(),
childstdoutrd,
GetCurrentProcess(),
&childstdoutrddup,
0,
FALSE,
DUPLICATE_SAME_ACCESS))
{
CloseHandle(childstdoutrd);
CloseHandle(childstdoutwr);
return NULL;
}
CloseHandle(childstdoutrd);
ZeroMemory(&pi, sizeof(pi));
ZeroMemory(&si, sizeof(si));
si.cb = sizeof(si);
si.dwFlags = STARTF_USESTDHANDLES;
si.hStdError = childstdoutwr;
si.hStdOutput = childstdoutwr;
si.hStdInput = INVALID_HANDLE_VALUE;
if (CreateProcess(NULL,
cmd,
NULL,
NULL,
TRUE,
0,
NULL,
NULL,
&si,
&pi))
{
/* Successfully started the process */
char *lineptr;
ZeroMemory(line, maxsize);
/* Try to read at least one line from the pipe */
/* This may require more than one wait/read attempt */
for (lineptr = line; lineptr < line + maxsize - 1;)
{
DWORD bytesread = 0;
/* Let's see if we can read */
if (WaitForSingleObject(childstdoutrddup, 10000) != WAIT_OBJECT_0)
break; /* Timeout, but perhaps we got a line already */
if (!ReadFile(childstdoutrddup, lineptr, maxsize - (lineptr - line),
&bytesread, NULL))
break; /* Error, but perhaps we got a line already */
lineptr += strlen(lineptr);
if (!bytesread)
break; /* EOF */
if (strchr(line, '\n'))
break; /* One or more lines read */
}
if (lineptr != line)
{
/* OK, we read some data */
int len;
/* If we got more than one line, cut off after the first \n */
lineptr = strchr(line, '\n');
if (lineptr)
*(lineptr + 1) = '\0';
len = strlen(line);
/*
* If EOL is \r\n, convert to just \n. Because stdout is a
* text-mode stream, the \n output by the child process is
* received as \r\n, so we convert it to \n. The server main.c
* sets setvbuf(stdout, NULL, _IONBF, 0) which has the effect of
* disabling \n to \r\n expansion for stdout.
*/
if (len >= 2 && line[len - 2] == '\r' && line[len - 1] == '\n')
{
line[len - 2] = '\n';
line[len - 1] = '\0';
len--;
}
/*
* We emulate fgets() behaviour. So if there is no newline at the
* end, we add one...
*/
if (len == 0 || line[len - 1] != '\n')
strcat(line, "\n");
retval = line;
}
CloseHandle(pi.hProcess);
CloseHandle(pi.hThread);
}
CloseHandle(childstdoutwr);
CloseHandle(childstdoutrddup);
return retval;
#endif /* WIN32 */
}