Fix handling of trailing spaces when decoding PEM files

Reported via [0].

[0] https://github.com/DCIT/perl-CryptX/issues/110#issuecomment-2407279713

Signed-off-by: Steffen Jaeckel <s@jaeckel.eu>

src/misc/pem/pem_read.c

@@ -43,6 +43,25 @@ static void s_unget_line(char *buf, unsigned long buflen, struct get_char *g)
    COPY_STR(g->unget_buf, buf, buflen);
 }
 
+static void s_tts(char *buf, unsigned long *buflen)
+{
+   while(1) {
+      unsigned long blen = *buflen;
+      if (blen < 2)
+         return;
+      blen--;
+      switch (buf[blen]) {
+         case ' ':
+         case '\t':
+            buf[blen] = '\0';
+            *buflen = blen;
+            break;
+         default:
+            return;
+      }
+   }
+}
+
 static char* s_get_line(char *buf, unsigned long *buflen, struct get_char *g)
 {
    unsigned long blen = 0;
@@ -64,11 +83,13 @@ static char* s_get_line(char *buf, unsigned long *buflen, struct get_char *g)
          if (c_ == '\r') {
             buf[--blen] = '\0';
          }
+         s_tts(buf, &blen);
          *buflen = blen;
          return buf;
       }
       if (c == -1 || c == '\0') {
          buf[blen] = '\0';
+         s_tts(buf, &blen);
          *buflen = blen;
          return buf;
       }

tests/pem/pkcs/extra/rsa_cryptx_issue110_2407279713

@@ -0,0 +1,27 @@
+-----BEGIN RSA PRIVATE KEY-----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+-----END RSA PRIVATE KEY-----