singleurl: fix query_is_modified

[emanuele6]

query_is_modified is global and does not get reset at every call of singleurl() so, if a query is modified for a URL, the query for all the following URLs is automatically considered modified.

Additionally --trim and --replace were setting query_is_modified to true unconditionally as long as a --trim or --replace option is passed to trurl, even if no changes were made.
Which made it effectively just a convoluted way to check if any of --trim, --replace, --append query, --sort-query was passed.

Since singleurl() was made recursive to implement --iterate, I could not just add query_is_modified = false at the start of singleurl() to fix the problem, so I have refactored the code to not need a global.

[emanuele6]

Wouldn't continue make more sense if it does not just fail? Or wouldn't it make more sense to just error instead of possibly outputting a wrong result?

[bagder]

Either this should exit immediately with an error, or we need to make the function return an error code so that the parent caller can spot the error. We should not let it continue and output wrong.

[emanuele6]

Currently this return is just ignored, as if this and the following --trims didn't match anything

[bagder]

It would be most helpful if you also added a test case for the scenario this fixes.

[emanuele6]

@bagder This doesn't fix behaviour; it fixes query_is_modified being set to true unnecessarily, making trurl do extra work unnecessarily.

[bagder]

ah thanks, I missed that nuance

[emanuele6]

For example:
ltrace trurl --replace 'a=x' 'https://example.com/?'{a,b}'=z' without the patch:

 strchr("b=z", '&')                                                                                       = nil
 strlen("b=z")                                                                                            = 3
 malloc(16)                                                                                               = 0x559e1dcfade0
 malloc(4)                                                                                                = 0x559e1dcfa240
 memcpy(0x559e1dcfa240, "b=z", 3)                                                                         = 0x559e1dcfa240
 memchr("b=z", '=', 3)                                                                                    = 0x559e1dcf9fd1
 curl_easy_unescape(0, 0x559e1dcf9fd0, 1, 0x7fff2da4b144)                                                 = 0x559e1dd00390
 curl_easy_unescape(0, 0x559e1dcf9fd2, 1, 0x7fff2da4b140)                                                 = 0x559e1dcfa010
 malloc(3)                                                                                                = 0x559e1dd00370
 memcpy(0x559e1dd00370, "b", 1)                                                                           = 0x559e1dd00370
 memcpy(0x559e1dd00372, "z", 1)                                                                           = 0x559e1dd00372
 curl_free(0x559e1dcfa010, 0x559e1dcfa010, 1, 122)                                                        = 1
 curl_free(0x559e1dd00390, 0x559e1dcfa000, 0x559e1dcfa, 33)                                               = 2
 malloc(16)                                                                                               = 0x559e1dd00390
 free(0x559e1dd00390)                                                                                     = <void>
 free(0x559e1dcfade0)                                                                                     = <void>
 curl_free(0x559e1dcf9fd0, 0x559e1dcfadd0, 0x559b4431df6a, 33)                                            = 4
 strchr("a=x", '=')                                                                                       = "=x"
 strlen("x")                                                                                              = 1
 strncmp("b=z", "a=x", 1)                                                                                 = 1
+curl_maprintf(0x559e1d917138, 0x559e1d91718a, 0x559e1d91718a, 0x559e1dcfa240)                            = 0x559e1dcfb7b0
+curl_free(0, 0x7fff2da496b7, 0, 122)                                                                     = 0x7fe38bbfb5b8
+curl_url_set(0x559e1dd01180, 8, 0x559e1dcfb7b0, 0)                                                       = 0
+curl_free(0x559e1dcfb7b0, 0x559e1dcfc040, 0x559e1dcfc, 0x559e1dcf9fd0)                                   = 2
 curl_url_get(0x559e1dd01180, 0, 0x7fff2da4b230, 74)                                                      = 0
 puts("https://example.com/?b=z")                                                                         = 25

ltrace ./trurl --replace 'a=x' 'https://example.com/?'{a,b}'=z' with the patch:

[...]
 strchr("b=z", '&')                                                                                       = nil
 strlen("b=z")                                                                                            = 3
 malloc(16)                                                                                               = 0x557cb7b49de0
 malloc(4)                                                                                                = 0x557cb7b49240
 memcpy(0x557cb7b49240, "b=z", 3)                                                                         = 0x557cb7b49240
 memchr("b=z", '=', 3)                                                                                    = 0x557cb7b48fd1
 curl_easy_unescape(0, 0x557cb7b48fd0, 1, 0x7ffdb4e9bac0)                                                 = 0x557cb7b4f390
 curl_easy_unescape(0, 0x557cb7b48fd2, 1, 0x7ffdb4e9babc)                                                 = 0x557cb7b49010
 malloc(3)                                                                                                = 0x557cb7b4f370
 memcpy(0x557cb7b4f370, "b", 1)                                                                           = 0x557cb7b4f370
 memcpy(0x557cb7b4f372, "z", 1)                                                                           = 0x557cb7b4f372
 curl_free(0x557cb7b49010, 0x557cb7b49010, 1, 0x557cb7b4f37a)                                             = 1
 curl_free(0x557cb7b4f390, 0x557cb7b49000, 0x557cb7b49, 33)                                               = 2
 malloc(16)                                                                                               = 0x557cb7b4f390
 free(0x557cb7b4f390)                                                                                     = <void>
 free(0x557cb7b49de0)                                                                                     = <void>
 curl_free(0x557cb7b48fd0, 0x557cb7b49dd0, 0x5579e07f88d9, 33)                                            = 4
 strchr("a=x", '=')                                                                                       = "=x"
 strlen("x")                                                                                              = 1
 strncmp("b=z", "a=x", 1)                                                                                 = 1
-curl_maprintf
-curl_free
-curl_url_set
-curl_free
 curl_url_get(0x557cb7b50180, 0, 0x7ffdb4e9bc50, 74)                                                      = 0
 puts("https://example.com/?b=z")                                                                         = 25
[...]

[bagder]

Thanks!