From 3ae9ce5dd7d1119ca2c94c63a07b04921048ebe3 Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Wed, 14 Feb 2018 20:11:16 -0700 Subject: [PATCH] Special case NULL when using printf's %s format This changes the printf command's %s and %ls formats to special-case NULL, and print "(null)" for these. This is PR cli/14977. This behavior seems a bit friendlier; I was undecided on whether other invalid pointers should be handled specially somehow, so for the time being I've left those out. gdb/ChangeLog 2018-03-14 Tom Tromey PR cli/14977: * printcmd.c (printf_c_string, printf_wide_c_string): Special case for NULL. gdb/gdbserver/ChangeLog 2018-03-14 Tom Tromey PR cli/14977: * ax.c (ax_printf): Special case for NULL. gdb/testsuite/ChangeLog 2018-03-14 Tom Tromey PR cli/14977: * gdb.base/printcmds.exp (test_printf): Add printf test of %s with a null pointer. * gdb.base/wchar.exp: Likewise. --- gdb/ChangeLog | 6 ++++++ gdb/gdbserver/ChangeLog | 5 +++++ gdb/gdbserver/ax.c | 5 +++++ gdb/printcmd.c | 10 ++++++++++ gdb/testsuite/ChangeLog | 7 +++++++ gdb/testsuite/gdb.base/printcmds.exp | 3 +++ gdb/testsuite/gdb.base/wchar.exp | 3 +++ 7 files changed, 39 insertions(+) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index da59b39f4e7..a62255fb035 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,9 @@ +2018-03-14 Tom Tromey + + PR cli/14977: + * printcmd.c (printf_c_string, printf_wide_c_string): Special case + for NULL. + 2018-03-14 Tom Tromey PR cli/19918: diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog index 053cf17ee52..2be87a64288 100644 --- a/gdb/gdbserver/ChangeLog +++ b/gdb/gdbserver/ChangeLog @@ -1,3 +1,8 @@ +2018-03-14 Tom Tromey + + PR cli/14977: + * ax.c (ax_printf): Special case for NULL. + 2018-03-08 Simon Marchi * linux-low.c (linux_qxfer_libraries_svr4): Use diff --git a/gdb/gdbserver/ax.c b/gdb/gdbserver/ax.c index b42ee54c84f..c754383df8f 100644 --- a/gdb/gdbserver/ax.c +++ b/gdb/gdbserver/ax.c @@ -847,6 +847,11 @@ ax_printf (CORE_ADDR fn, CORE_ADDR chan, const char *format, int j; tem = args[i]; + if (tem == 0) + { + printf (current_substring, "(null)"); + break; + } /* This is a %s argument. Find the length of the string. */ for (j = 0;; j++) diff --git a/gdb/printcmd.c b/gdb/printcmd.c index 17c67eee4e5..9fb2e026dfa 100644 --- a/gdb/printcmd.c +++ b/gdb/printcmd.c @@ -2220,6 +2220,11 @@ printf_c_string (struct ui_file *stream, const char *format, int j; tem = value_as_address (value); + if (tem == 0) + { + fprintf_filtered (stream, format, "(null)"); + return; + } /* This is a %s argument. Find the length of the string. */ for (j = 0;; j++) @@ -2260,6 +2265,11 @@ printf_wide_c_string (struct ui_file *stream, const char *format, gdb_byte *buf = (gdb_byte *) alloca (wcwidth); tem = value_as_address (value); + if (tem == 0) + { + fprintf_filtered (stream, format, "(null)"); + return; + } /* This is a %s argument. Find the length of the string. */ for (j = 0;; j += wcwidth) diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index abac29fae13..f31f91e8f62 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,10 @@ +2018-03-14 Tom Tromey + + PR cli/14977: + * gdb.base/printcmds.exp (test_printf): Add printf test of %s with + a null pointer. + * gdb.base/wchar.exp: Likewise. + 2018-03-14 Tom Tromey PR cli/19918: diff --git a/gdb/testsuite/gdb.base/printcmds.exp b/gdb/testsuite/gdb.base/printcmds.exp index 56cedb908f1..635bd621fda 100644 --- a/gdb/testsuite/gdb.base/printcmds.exp +++ b/gdb/testsuite/gdb.base/printcmds.exp @@ -780,6 +780,9 @@ proc test_printf {} { # PR cli/19918. gdb_test "printf \"%-16dq\\n\", 0" "0 q" gdb_test "printf \"%-16pq\\n\", 0" "\\(nil\\) q" + + # PR cli/14977. + gdb_test "printf \"%s\\n\", 0" "\\(null\\)" } #Test printing DFP values with printf diff --git a/gdb/testsuite/gdb.base/wchar.exp b/gdb/testsuite/gdb.base/wchar.exp index 80b6513e222..a4d9bce7d0f 100644 --- a/gdb/testsuite/gdb.base/wchar.exp +++ b/gdb/testsuite/gdb.base/wchar.exp @@ -69,3 +69,6 @@ gdb_test "print repeat" "= L\"A$cent$cent\"\.\.\." \ gdb_test "print repeat_p" "= $hex L\"A$cent$cent\"\.\.\." \ "print repeat_p (print elements 3)" + +# From PR cli/14977, but here because it requires wchar_t. +gdb_test "printf \"%ls\\n\", 0" "\\(null\\)" -- 2.30.2