Libguestfs - Jul 2017 - [PATCH] common/mlstdutils: Add chomp function to remove \n from end of strings.

This is like the Perl chomp function, it removes a single \n from the
end of a string if present, else leaves the string alone.

I believe I found the only (two) places where such a function is used,
but there may be a few more lurking.
---
 common/mlstdutils/std_utils.ml       |  7 +++++++
 common/mlstdutils/std_utils.mli      |  2 ++
 common/mlstdutils/std_utils_tests.ml | 10 ++++++++++
 mllib/common_utils.ml                | 10 ++--------
 v2v/linux_bootloaders.ml             |  8 ++------
 5 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/common/mlstdutils/std_utils.ml b/common/mlstdutils/std_utils.ml
index 374507662..b731b8fd5 100644
--- a/common/mlstdutils/std_utils.ml
+++ b/common/mlstdutils/std_utils.ml
@@ -229,6 +229,13 @@ module String = struct
     let trim ?(test = Char.isspace) str        trimr ~test (triml ~test str)
 
+    let chomp str +      let n = String.length str in
+      if n > 0 && str.[n-1] = '\n' then
+        String.sub str 0 (n-1)
+      else
+        str
+
     let count_chars c str        let count = ref 0 in
       for i = 0 to String.length str - 1 do
diff --git a/common/mlstdutils/std_utils.mli b/common/mlstdutils/std_utils.mli
index 0b7d90736..d217e48d4 100644
--- a/common/mlstdutils/std_utils.mli
+++ b/common/mlstdutils/std_utils.mli
@@ -107,6 +107,8 @@ module String : sig
     (** Trim right. *)
     val trim : ?test:(char -> bool) -> string -> string
     (** Trim left and right. *)
+    val chomp : string -> string
+    (** If the string ends with [\n], remove it. *)
     val count_chars : char -> string -> int
     (** Count number of times the character occurs in string. *)
     val explode : string -> char list
diff --git a/common/mlstdutils/std_utils_tests.ml
b/common/mlstdutils/std_utils_tests.ml
index 2789766c6..ce49c7606 100644
--- a/common/mlstdutils/std_utils_tests.ml
+++ b/common/mlstdutils/std_utils_tests.ml
@@ -110,6 +110,15 @@ let test_string_span ctx    assert_equal_int 3
(String.cspan "def" "ab");
   assert_equal_int 0 (String.cspan "" "ab")
 
+(* Test Std_utils.String.chomp. *)
+let test_string_chomp ctx +  assert_equal_string "a" (String.chomp
"a");
+  assert_equal_string "a" (String.chomp "a\n");
+  assert_equal_string "a\nb" (String.chomp "a\nb");
+  assert_equal_string "" (String.chomp "");
+  assert_equal_string "" (String.chomp "\n");
+  assert_equal_string "\n" (String.chomp "\n\n") (* only
removes one *)
+
 (* Suites declaration. *)
 let suite    "mllib Std_utils" >:::
@@ -122,6 +131,7 @@ let suite        "strings.find" >::
test_string_find;
       "strings.lines_split" >:: test_string_lines_split;
       "strings.span" >:: test_string_span;
+      "strings.chomp" >:: test_string_chomp;
     ]
 
 let () diff --git a/mllib/common_utils.ml b/mllib/common_utils.ml
index 73c6e2473..597128967 100644
--- a/mllib/common_utils.ml
+++ b/mllib/common_utils.ml
@@ -376,14 +376,8 @@ let shell_command ?(echo_cmd = true) cmd  let uuidgen ()   
let lines = external_command "uuidgen -r" in
   assert (List.length lines >= 1);
-  let uuid = List.hd lines in
-  let len = String.length uuid in
-  let uuid, len -    if len > 0 && uuid.[len-1] = '\n' then
-      String.sub uuid 0 (len-1), len-1
-    else
-      uuid, len in
-  if len < 10 then assert false; (* sanity check on uuidgen *)
+  let uuid = String.chomp (List.hd lines) in
+  if String.length uuid < 10 then assert false; (* sanity check on uuidgen
*)
   uuid
 
 (* Remove a temporary directory on exit. *)
diff --git a/v2v/linux_bootloaders.ml b/v2v/linux_bootloaders.ml
index d76407670..210cce762 100644
--- a/v2v/linux_bootloaders.ml
+++ b/v2v/linux_bootloaders.ml
@@ -307,12 +307,8 @@ object (self)
       match res with
       | None -> None
       | Some k ->
-        let len = String.length k in
-        let k -          if len > 0 && k.[len-1] = '\n' then
-            String.sub k 0 (len-1)
-          else k in
-        Some (remove_hd_prefix k)
+         let k = String.chomp k in
+         Some (remove_hd_prefix k)
     in
 
     let vmlinuzes -- 
2.13.2

On Friday, 21 July 2017 15:56:17 CEST Richard W.M. Jones
wrote:
> This is like the Perl chomp function, it removes a single \n from the
> end of a string if present, else leaves the string alone.
> 
> I believe I found the only (two) places where such a function is used,
> but there may be a few more lurking.
> ---
I did not find more either -- LGTM.

-- 
Pino Toscano

Checking out sources from https://github.com/libguestfs/libguestfs ...

/var/tmp/tmpZ6wS6s/libguestfs /var/tmp/tmpZ6wS6s
Reset branch 'master'
Branch master set up to track remote branch master from origin.
Your branch is up-to-date with 'origin/master'.
Already up-to-date.
/var/tmp/tmpZ6wS6s

Applying patches ...

/var/tmp/tmpZ6wS6s/libguestfs /var/tmp/tmpZ6wS6s
error: patch failed: common/mlstdutils/std_utils.ml:229
error: common/mlstdutils/std_utils.ml: patch does not apply
error: patch failed: common/mlstdutils/std_utils.mli:107
error: common/mlstdutils/std_utils.mli: patch does not apply
error: patch failed: common/mlstdutils/std_utils_tests.ml:110
error: common/mlstdutils/std_utils_tests.ml: patch does not apply
error: patch failed: mllib/common_utils.ml:376
error: mllib/common_utils.ml: patch does not apply
error: patch failed: v2v/linux_bootloaders.ml:307
error: v2v/linux_bootloaders.ml: patch does not apply
Applying: common/mlstdutils: Add chomp function to remove \n from end of
strings.
Patch failed at 0001 common/mlstdutils: Add chomp function to remove \n from end
of strings.
The copy of the patch that failed is found in: .git/rebase-apply/patch
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am
--abort".

Checking out sources from https://github.com/libguestfs/libguestfs ...

/var/tmp/tmpCbDvGx/libguestfs /var/tmp/tmpCbDvGx
Reset branch 'master'
Branch master set up to track remote branch master from origin.
Your branch is up-to-date with 'origin/master'.
Already up-to-date.
/var/tmp/tmpCbDvGx

Applying patches ...

/var/tmp/tmpCbDvGx/libguestfs /var/tmp/tmpCbDvGx
error: patch failed: common/mlstdutils/std_utils.ml:229
error: common/mlstdutils/std_utils.ml: patch does not apply
error: patch failed: common/mlstdutils/std_utils.mli:107
error: common/mlstdutils/std_utils.mli: patch does not apply
error: patch failed: common/mlstdutils/std_utils_tests.ml:110
error: common/mlstdutils/std_utils_tests.ml: patch does not apply
error: patch failed: mllib/common_utils.ml:376
error: mllib/common_utils.ml: patch does not apply
error: patch failed: v2v/linux_bootloaders.ml:307
error: v2v/linux_bootloaders.ml: patch does not apply
Applying: common/mlstdutils: Add chomp function to remove \n from end of
strings.
Patch failed at 0001 common/mlstdutils: Add chomp function to remove \n from end
of strings.
The copy of the patch that failed is found in: .git/rebase-apply/patch
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am
--abort".