From 7590d0625ba6e994a00191aa708d3aadee70c407 Mon Sep 17 00:00:00 2001
From: Simon Tatham <anakin@pobox.com>
Date: Wed, 22 Jan 2020 22:24:41 +0000
Subject: [PATCH] Introduce and use strbuf_chomp.

Those chomp operations in wincons.c and uxcons.c looked ugly, and I'm
not totally convinced they couldn't underrun the buffer by 1 byte in
weird circumstances. strbuf_chomp is neater.
---
 misc.h            | 1 +
 scpserver.c       | 2 +-
 unix/uxcons.c     | 4 +---
 utils.c           | 9 +++++++++
 windows/wincons.c | 6 ++----
 5 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/misc.h b/misc.h
index dfc6659d..51155a21 100644
--- a/misc.h
+++ b/misc.h
@@ -79,6 +79,7 @@ char *strbuf_to_str(strbuf *buf); /* does free buf, but you must free result */
 void strbuf_catf(strbuf *buf, const char *fmt, ...);
 void strbuf_catfv(strbuf *buf, const char *fmt, va_list ap);
 static inline void strbuf_clear(strbuf *buf) { strbuf_shrink_to(buf, 0); }
+bool strbuf_chomp(strbuf *buf, char char_to_remove);
 
 strbuf *strbuf_new_for_agent_query(void);
 void strbuf_finalise_agent_query(strbuf *buf);
diff --git a/scpserver.c b/scpserver.c
index 3123dc16..e594f1ab 100644
--- a/scpserver.c
+++ b/scpserver.c
@@ -1095,7 +1095,7 @@ static void scp_sink_coroutine(ScpSink *scp)
         /*
          * Parse the command.
          */
-        strbuf_shrink_by(scp->command, 1); /* chomp the newline */
+        strbuf_chomp(scp->command, '\n');
         scp->command_chr = scp->command->len > 0 ? scp->command->s[0] : '\0';
         if (scp->command_chr == 'T') {
             unsigned long dummy1, dummy2;
diff --git a/unix/uxcons.c b/unix/uxcons.c
index 3e8a7ea5..da7b8935 100644
--- a/unix/uxcons.c
+++ b/unix/uxcons.c
@@ -592,10 +592,8 @@ int console_get_userpass_input(prompts_t *p)
             }
 
             strbuf_shrink_to(pr->result, prev_result_len + ret);
-            if (pr->result->s[pr->result->len - 1] == '\n') {
-                strbuf_shrink_by(pr->result, 1);
+            if (strbuf_chomp(pr->result, '\n'))
                 break;
-            }
         }
 
         tcsetattr(infd, TCSANOW, &oldmode);
diff --git a/utils.c b/utils.c
index 667281d6..5acb53cb 100644
--- a/utils.c
+++ b/utils.c
@@ -443,6 +443,15 @@ void strbuf_shrink_by(strbuf *buf, size_t amount_to_remove)
     buf->s[buf->len] = '\0';
 }
 
+bool strbuf_chomp(strbuf *buf, char char_to_remove)
+{
+    if (buf->len > 0 && buf->s[buf->len-1] == char_to_remove) {
+        strbuf_shrink_by(buf, 1);
+        return true;
+    }
+    return false;
+}
+
 static void strbuf_BinarySink_write(
     BinarySink *bs, const void *data, size_t len)
 {
diff --git a/windows/wincons.c b/windows/wincons.c
index d91d9cef..4fb5eb3f 100644
--- a/windows/wincons.c
+++ b/windows/wincons.c
@@ -515,10 +515,8 @@ int console_get_userpass_input(prompts_t *p)
             }
 
             strbuf_shrink_to(pr->result, prev_result_len + ret);
-            if (pr->result->s[pr->result->len - 1] == '\n') {
-                strbuf_shrink_by(pr->result, 1);
-                if (pr->result->s[pr->result->len - 1] == '\r')
-                    strbuf_shrink_by(pr->result, 1);
+            if (strbuf_chomp(pr->result, '\n')) {
+                strbuf_chomp(pr->result, '\r');
                 break;
             }
         }