Merge remote-tracking branch 'aosp/upstream-master' into mymerge am: 2e0d635a87 am: 3dac286b93 am: 7ef808bcfa

Change-Id: I195127d7fcb35686c41a0095d886ba39da60bc5c

3 files changed, 38 insertions, 33 deletions

diff --git a/examples/debug_output.sh b/examples/debug_output.sh
index b3ecec2..a5e61c8 100755
--- a/examples/debug_output.sh
+++ b/examples/debug_output.sh
@@ -11,10 +11,10 @@
 # $ ./debug_output.sh sing
 # $ ./debug_output.sh --debug sing
 
-# source shflags
-. ../src/shflags
+# Source shflags.
+. ../shflags
 
-# define flags
+# Define flags.
 DEFINE_boolean 'debug' false 'enable debug mode' 'd'
 FLAGS_HELP=`cat <<EOF
 commands:
@@ -22,21 +22,17 @@ commands:
   sing:   sing something
 EOF`
 
-
-debug()
-{
+debug() {
   [ ${FLAGS_debug} -eq ${FLAGS_TRUE} ] || return
   echo "DEBUG: $@" >&2
 }
 
-die() {
-  [ $# -gt 0 ] && echo "error: $@" >&2
+die() { [ $# -gt 0 ] && echo "error: $@" >&2
   flags_help
   exit 1
 }
 
-
-# parse the command-line
+# Parse the command-line.
 FLAGS "$@" || exit 1
 eval set -- "${FLAGS_ARGV}"
 
diff --git a/examples/hello_world.sh b/examples/hello_world.sh
index 84b755a..e5fe81c 100755
--- a/examples/hello_world.sh
+++ b/examples/hello_world.sh
@@ -7,13 +7,13 @@
 # '--name'). If a name is given, it is output, otherwise the default of 'world'
 # is output.
 
-# source shflags
-. ../src/shflags
+# Source shflags.
+. ../shflags
 
-# define a 'name' command-line string flag
+# Define a 'name' command-line string flag.
 DEFINE_string 'name' 'world' 'name to say hello to' 'n'
 
-# parse the command-line
+# Parse the command-line.
 FLAGS "$@" || exit 1
 eval set -- "${FLAGS_ARGV}"
 
diff --git a/examples/write_date.sh b/examples/write_date.sh
index b8e610b..d9ae3ec 100755
--- a/examples/write_date.sh
+++ b/examples/write_date.sh
@@ -20,35 +20,44 @@
 # $ ./write_date.sh -f now.out
 # $ cat now.out
 
-# source shflags
-. ../src/shflags
+# Source shFlags.
+. ../shflags
 
-# configure shflags
+# Configure shFlags.
 DEFINE_boolean 'force' false 'force overwriting' 'f'
 FLAGS_HELP="USAGE: $0 [flags] filename"
 
-
-write_date()
-{
-  date >"$1"
-}
-
-die()
-{
-  [ $# -gt 0 ] && echo "error: $@" >&2
+die() {
+  [ $# -gt 0 ] && echo "error: $@"
   flags_help
   exit 1
 }
 
-
-# parse the command-line
+# Parse the command-line.
 FLAGS "$@" || exit 1
 eval set -- "${FLAGS_ARGV}"
 
-# check for filename
-[ $# -gt 0 ] || die 'filename missing'
+# Check for filename on command-line.
+[ $# -gt 0 ] || die 'filename missing.'
 filename=$1
 
-[ -f "${filename}" -a ${FLAGS_force} -eq ${FLAGS_FALSE} ] \
-    && die 'filename exists; not overwriting'
-write_date "${filename}"
+# Redirect STDOUT to the file ($1). This seemingly complicated method using exec
+# is used so that a potential race condition between checking for the presence
+# of the file and writing to the file is mitigated.
+if [ ${FLAGS_force} -eq ${FLAGS_FALSE} ] ; then
+  [ ! -f "${filename}" ] || die "file \"${filename}\" already exists."
+  # Set noclobber, redirect STDOUT to the file, first saving STDOUT to fd 4.
+  set -C
+  exec 4>&1 >"${filename}"  # This fails if the file exists.
+else
+  # Forcefully overwrite (clobber) the file.
+  exec 4>&1 >|"${filename}"
+fi
+
+# What time is it?
+date
+
+# Restore STDOUT from file descriptor 4, and close fd 4.
+exec 1>&4 4>&-
+
+echo "The current date was written to \"${filename}\"."