Fix some places where errno might not be preserved.

Author: michaelrsweet

backend/ipp.c

@@ -1,7 +1,7 @@
 /*
  * IPP backend for CUPS.
  *
- * Copyright © 2021-2025 by OpenPrinting
+ * Copyright © 2021-2026 by OpenPrinting
  * Copyright © 2007-2021 by Apple Inc.
  * Copyright © 1997-2007 by Easy Software Products, all rights reserved.
  *
@@ -718,7 +718,7 @@ main(int  argc,				/* I - Number of command-line args */
 
     if (httpReconnect2(http, 30000, NULL))
     {
-      int error = errno;		/* Connection error */
+      int error = errno;		/* Save connection error */
 
       if (http->status == HTTP_STATUS_CUPS_PKI_ERROR)
 	update_reasons(NULL, "+cups-certificate-error");
@@ -752,7 +752,7 @@ main(int  argc,				/* I - Number of command-line args */
 
       fprintf(stderr, "DEBUG: Connection error: %s\n", strerror(errno));
 
-      if (errno == ECONNREFUSED || errno == EHOSTDOWN || errno == EHOSTUNREACH || errno == ETIMEDOUT || errno == ENOTCONN)
+      if (error == ECONNREFUSED || error == EHOSTDOWN || error == EHOSTUNREACH || error == ETIMEDOUT || error == ENOTCONN)
       {
         if (contimeout && (time(NULL) - start_time) > contimeout)
 	{

backend/lpd.c

@@ -1,7 +1,7 @@
 /*
  * Line Printer Daemon backend for CUPS.
  *
- * Copyright © 2020-2024 by OpenPrinting.
+ * Copyright © 2020-2026 by OpenPrinting.
  * Copyright © 2007-2019 by Apple Inc.
  * Copyright © 1997-2007 by Easy Software Products, all rights reserved.
  *
@@ -863,7 +863,7 @@ lpd_queue(const char      *hostname,	/* I - Host to connect to */
 
       fprintf(stderr, "DEBUG: Connection error: %s\n", strerror(error));
 
-      if (errno == ECONNREFUSED || errno == EHOSTDOWN || errno == EHOSTUNREACH || errno == ETIMEDOUT || errno == ENOTCONN)
+      if (error == ECONNREFUSED || error == EHOSTDOWN || error == EHOSTUNREACH || error == ETIMEDOUT || error == ENOTCONN)
       {
         if (contimeout && (time(NULL) - start_time) > contimeout)
 	{

cups/debug.c

@@ -1,7 +1,7 @@
 /*
  * Debugging functions for CUPS.
  *
- * Copyright © 2020-2024 by OpenPrinting.
+ * Copyright © 2020-2026 by OpenPrinting.
  * Copyright © 2008-2018 by Apple Inc.
  *
  * Licensed under Apache License v2.0.  See the file "LICENSE" for more
@@ -89,6 +89,7 @@ _cups_debug_printf(const char *format,	/* I - Printf-style format string */
   char			buffer[2048];	/* Output buffer */
   ssize_t		bytes;		/* Number of bytes in buffer */
   int			level;		/* Log level in message */
+  int			myerrno = errno;/* Copy of errno value */
 
 
  /*
@@ -100,7 +101,7 @@ _cups_debug_printf(const char *format,	/* I - Printf-style format string */
                     getenv("CUPS_DEBUG_FILTER"), 0);
 
   if (_cups_debug_fd < 0)
-    return;
+    goto done;
 
  /*
   * Filter as needed...
@@ -112,7 +113,7 @@ _cups_debug_printf(const char *format,	/* I - Printf-style format string */
     level = 0;
 
   if (level > _cups_debug_level)
-    return;
+    goto done;
 
   if (debug_filter)
   {
@@ -123,7 +124,7 @@ _cups_debug_printf(const char *format,	/* I - Printf-style format string */
     _cupsMutexUnlock(&debug_init_mutex);
 
     if (result)
-      return;
+      goto done;
   }
 
  /*
@@ -158,6 +159,10 @@ _cups_debug_printf(const char *format,	/* I - Printf-style format string */
   _cupsMutexLock(&debug_log_mutex);
   write(_cups_debug_fd, buffer, (size_t)bytes);
   _cupsMutexUnlock(&debug_log_mutex);
+
+  done:
+
+  errno = myerrno;
 }
 
 
@@ -172,6 +177,7 @@ _cups_debug_puts(const char *s)		/* I - String to output */
   char			buffer[2048];	/* Output buffer */
   ssize_t		bytes;		/* Number of bytes in buffer */
   int			level;		/* Log level in message */
+  int			myerrno = errno;/* Copy of errno value */
 
 
  /*
@@ -183,7 +189,7 @@ _cups_debug_puts(const char *s)		/* I - String to output */
                     getenv("CUPS_DEBUG_FILTER"), 0);
 
   if (_cups_debug_fd < 0)
-    return;
+    goto done;
 
  /*
   * Filter as needed...
@@ -195,7 +201,7 @@ _cups_debug_puts(const char *s)		/* I - String to output */
     level = 0;
 
   if (level > _cups_debug_level)
-    return;
+    goto done;
 
   if (debug_filter)
   {
@@ -206,7 +212,7 @@ _cups_debug_puts(const char *s)		/* I - String to output */
     _cupsMutexUnlock(&debug_init_mutex);
 
     if (result)
-      return;
+      goto done;
   }
 
  /*
@@ -238,6 +244,10 @@ _cups_debug_puts(const char *s)		/* I - String to output */
   _cupsMutexLock(&debug_log_mutex);
   write(_cups_debug_fd, buffer, (size_t)bytes);
   _cupsMutexUnlock(&debug_log_mutex);
+
+  done:
+
+  errno = myerrno;
 }