Fix and test graph parsing (#1447)

* specials: comment all parser cases

* specials: scan_graph: early-return if args is null

* specials: fix logic in scan_graph

* tests: add scan_graph parsing test

* specials: separate command parsing from graph parsing

this simplifies the implementation of graph parsing and makes it less ambiguous to parse graphs in contexts where commands are not expected

* specials: tweak comments in scan_graph

* tests: update for scan_command separation

---------

Co-authored-by: bi4k8 <bi4k8@github>

src/common.cc

@@ -352,10 +352,7 @@ void print_no_update(struct text_object *obj, char *p,
 
 #ifdef BUILD_GUI
 void scan_loadgraph_arg(struct text_object *obj, const char *arg) {
-  char *buf = nullptr;
+  scan_graph(obj, arg, 0);
-
-  buf = scan_graph(obj, arg, 0);
-  free_and_zero(buf);
 }
 
 double loadgraphval(struct text_object *obj) {

src/core.cc

@@ -725,11 +725,9 @@ struct text_object *construct_text_object(char *s, const char *arg, long line,
   DBGP2("Adding $cpubar for CPU %d", obj->data.i);
 #ifdef BUILD_GUI
   END OBJ(cpugraph, &update_cpu_usage) get_cpu_count();
-  char *buf = nullptr;
   SCAN_CPU(arg, obj->data.i);
-  buf = scan_graph(obj, arg, 1);
+  scan_graph(obj, arg, 1);
   DBGP2("Adding $cpugraph for CPU %d", obj->data.i);
-  free_and_zero(buf);
   obj->callbacks.graphval = &cpu_barval;
   obj->callbacks.free = &free_cpu;
   END OBJ(loadgraph, &update_load_average) scan_loadgraph_arg(obj, arg);
@@ -1244,13 +1242,9 @@ struct text_object *construct_text_object(char *s, const char *arg, long line,
   END OBJ(memwithbuffersbar, &update_meminfo) scan_bar(obj, arg, 1);
   obj->callbacks.barval = &mem_with_buffers_barval;
 #ifdef BUILD_GUI
-  END OBJ(memgraph, &update_meminfo) char *buf = nullptr;
+  END OBJ(memgraph, &update_meminfo) scan_graph(obj, arg, 1);
-  buf = scan_graph(obj, arg, 1);
-  free_and_zero(buf);
   obj->callbacks.graphval = &mem_barval;
-  END OBJ(memwithbuffersgraph, &update_meminfo) char *buf = nullptr;
+  END OBJ(memwithbuffersgraph, &update_meminfo) scan_graph(obj, arg, 1);
-  buf = scan_graph(obj, arg, 1);
-  free_and_zero(buf);
   obj->callbacks.graphval = &mem_with_buffers_barval;
 #endif /* BUILD_GUI*/
 #ifdef HAVE_SOME_SOUNDCARD_H
@@ -1829,8 +1823,9 @@ struct text_object *construct_text_object(char *s, const char *arg, long line,
   END OBJ_ARG(
       lua_graph, nullptr,
       "lua_graph needs arguments: <function name> [height],[width] [gradient "
-      "colour 1] [gradient colour 2] [scale] [-t] [-l]") char *buf = nullptr;
+      "colour 1] [gradient colour 2] [scale] [-t] [-l]") auto [buf, skip] =
-  buf = scan_graph(obj, arg, 100);
+      scan_command(arg);
+  scan_graph(obj, arg + skip, 100);
   if (buf != nullptr) {
     obj->data.s = buf;
   } else {
@@ -1967,9 +1962,7 @@ struct text_object *construct_text_object(char *s, const char *arg, long line,
   END OBJ(apcupsd_loadbar, &update_apcupsd) scan_bar(obj, arg, 100);
   obj->callbacks.barval = &apcupsd_loadbarval;
 #ifdef BUILD_GUI
-  END OBJ(apcupsd_loadgraph, &update_apcupsd) char *buf = nullptr;
+  END OBJ(apcupsd_loadgraph, &update_apcupsd) scan_graph(obj, arg, 100);
-  buf = scan_graph(obj, arg, 100);
-  free_and_zero(buf);
   obj->callbacks.graphval = &apcupsd_loadbarval;
   END OBJ(apcupsd_loadgauge, &update_apcupsd) scan_gauge(obj, arg, 100);
   obj->callbacks.gaugeval = &apcupsd_loadbarval;

src/diskio.cc

@@ -172,8 +172,8 @@ void print_diskio_write(struct text_object *obj, char *p,
 
 #ifdef BUILD_GUI
 void parse_diskiograph_arg(struct text_object *obj, const char *arg) {
-  char *buf = nullptr;
+  auto [buf, skip] = scan_command(arg);
-  buf = scan_graph(obj, arg, 0);
+  scan_graph(obj, arg + skip, 0);
 
   obj->data.opaque = prepare_diskio_stat(dev_name(buf));
   free_and_zero(buf);

src/exec.cc

@@ -274,7 +274,9 @@ void scan_exec_arg(struct text_object *obj, const char *arg,
   } else if ((execflag & EF_GAUGE) != 0u) {
     cmd = scan_gauge(obj, cmd, 100);
   } else if ((execflag & EF_GRAPH) != 0u) {
-    cmd = scan_graph(obj, cmd, 100);
+    auto [buf, skip] = scan_command(cmd);
+    scan_graph(obj, cmd + skip, 100);
+    cmd = buf;
     if (cmd == nullptr) {
       NORM_ERR("error parsing arguments to execgraph object");
     }

src/net_stat.cc

@@ -333,8 +333,8 @@ void print_v6addrs(struct text_object *obj, char *p, unsigned int p_max_size) {
 void parse_net_stat_graph_arg(struct text_object *obj, const char *arg,
                               void *free_at_crash) {
   /* scan arguments and get interface name back */
-  char *buf = nullptr;
+  auto [buf, skip] = scan_command(arg);
-  buf = scan_graph(obj, arg, 0);
+  scan_graph(obj, arg + skip, 0);
 
   // default to DEFAULTNETDEV
   if (buf != nullptr) {

src/nvidia.cc

@@ -454,9 +454,11 @@ int set_nvidia_query(struct text_object *obj, const char *arg,
     case BAR:
       arg = scan_bar(obj, arg, 100);
       break;
-    case GRAPH:
+    case GRAPH: {
-      arg = scan_graph(obj, arg, 100);
+      auto [buf, skip] = scan_command(arg);
-      break;
+      scan_graph(obj, arg + skip, 100);
+      arg = buf;
+    } break;
     case GAUGE:
       arg = scan_gauge(obj, arg, 100);
       break;

src/specials.cc

@@ -199,6 +199,45 @@ void apply_graph_colours(struct graph *g, const char *first_colour_name,
   g->colours_set = true;
 }
 
+/**
+ * parses a possibly-quoted command from the prefix of a string.
+ * @param[in] s argument string to parse
+ * @return pair of the command and the number of bytes parsed (counting quotes).
+ *         The command will be nullptr if the string to parse started with a
+ *         digit or an unpaired double-quote.
+ **/
+std::pair<char *, size_t> scan_command(const char *s) {
+  if (s == nullptr) return {nullptr, 0};
+
+  /* unquoted commands are not permitted to begin with digits. This allows
+  distinguishing a commands from a position in execgraph objects */
+  if (isdigit(*s)) { return {nullptr, 0}; }
+
+  /* extract double-quoted command in case of execgraph */
+  if (*s == '"') {
+    size_t _size;
+    char *_ptr;
+    if (((_ptr = const_cast<char *>(strrchr(s, '"'))) != nullptr) &&
+        _ptr != s) {
+      _size = _ptr - s - 1;
+    } else {
+      NORM_ERR("mismatched double-quote in execgraph object");
+      return {nullptr, 0};
+    }
+
+    char *quoted_cmd = static_cast<char *>(malloc(_size + 1));
+    quoted_cmd[0] = '\0';
+    strncpy(quoted_cmd, s + 1, _size);
+    quoted_cmd[_size] = '\0';
+    return {quoted_cmd, _size + 2};
+  } else {
+    size_t len;
+    for (len = 0; s[len] != '\0' && !isspace(s[len]); len++)
+      ;
+    return {strndup(s, len), len};
+  }
+}
+
 /**
  * parses for [height,width] [color1 color2] [scale] [-t] [-l]
  *
@@ -208,13 +247,9 @@ void apply_graph_colours(struct graph *g, const char *first_colour_name,
  * @param[out] obj  struct in which to save width, height and other options
  * @param[in]  args argument string to parse
  * @param[in]  defscale default scale if no scale argument given
- * @return string to the command argument, nullptr if argument didn't start with
+ * @return whether parsing was successful
- *         a string, but a number or if invalid argument string
  **/
-char *scan_graph(struct text_object *obj, const char *args, double defscale) {
+bool scan_graph(struct text_object *obj, const char *argstr, double defscale) {
-  char quoted_cmd[1024] = {'\0'}; /* double-quoted execgraph command */
-  char argstr[1024] = {'\0'};     /* args minus quoted_cmd */
-  char buf[1024] = {'\0'};        /* first unquoted string argument in argstr */
   char first_colour_name[1024] = {'\0'};
   char last_colour_name[1024] = {'\0'};
 
@@ -222,8 +257,8 @@ char *scan_graph(struct text_object *obj, const char *args, double defscale) {
   memset(g, 0, sizeof(struct graph));
   obj->special_data = g;
 
-  /* zero width means all space that is available */
   g->id = ++graph_count;
+  /* zero width means all space that is available */
   g->width = default_graph_width.get(*state);
   g->height = default_graph_height.get(*state);
   g->colours_set = false;
@@ -231,135 +266,87 @@ char *scan_graph(struct text_object *obj, const char *args, double defscale) {
   g->last_colour = Colour();
   g->scale = defscale;
   g->tempgrad = FALSE;
-  if (args != nullptr) {
-    /* extract double-quoted command in case of execgraph */
-    if (*args == '"') {
-      char *_ptr;
-      size_t _size;
-      if (((_ptr = const_cast<char *>(strrchr(args, '"'))) != nullptr) &&
-          _ptr != args) {
-        _size = _ptr - args - 1;
-      } else {
-        NORM_ERR("mismatched double-quote in execgraph object");
-        return nullptr;
-      }
 
-      _size = _size < 1024 ? _size : 1023;
+  if (argstr == nullptr) return false;
-      strncpy(quoted_cmd, args + 1, _size);
-      quoted_cmd[_size] = '\0';
 
-      /* copy everything after the last quote into argstr */
+  /* set tempgrad to true if '-t' specified.
-      if (_size + 2 < strlen(args)) { strncpy(argstr, args + _size + 2, 1023); }
+   * It doesn't matter where the argument is exactly. */
-    } else {
+  if ((strstr(argstr, " " TEMPGRAD) != nullptr) ||
-      /* redundant, but simplifies the code below */
+      strncmp(argstr, TEMPGRAD, strlen(TEMPGRAD)) == 0) {
-      strncpy(argstr, args, 1023);
+    g->tempgrad = TRUE;
-    }
+  }
-
+  /* set showlog flag if '-l' specified.
-    /* set tempgrad to true, if '-t' specified.
+   * It doesn't matter where the argument is exactly. */
-     * It doesn#t matter where the argument is exactly. */
+  if ((strstr(argstr, " " LOGGRAPH) != nullptr) ||
-    if ((strstr(argstr, " " TEMPGRAD) != nullptr) ||
+      strncmp(argstr, LOGGRAPH, strlen(LOGGRAPH)) == 0) {
-        strncmp(argstr, TEMPGRAD, strlen(TEMPGRAD)) == 0) {
+    g->flags |= SF_SHOWLOG;
-      g->tempgrad = TRUE;
-    }
-    /* set showlog-flag, if '-l' specified
-     * It doesn#t matter where the argument is exactly. */
-    if ((strstr(argstr, " " LOGGRAPH) != nullptr) ||
-        strncmp(argstr, LOGGRAPH, strlen(LOGGRAPH)) == 0) {
-      g->flags |= SF_SHOWLOG;
-    }
-
-    /* all the following functions try to interpret the beginning of a
-     * a string with different formaters. If successfully the return from
-     * this whole function */
-
-    /* interpret the beginning(!) of the argument string as:
-     * '[height],[width] [color1] [color2] [scale]'
-     * This means parameters like -t and -l may not be in the beginning */
-    if (sscanf(argstr, "%d,%d %s %s %lf", &g->height, &g->width,
-               first_colour_name, last_colour_name, &g->scale) == 5) {
-      apply_graph_colours(g, first_colour_name, last_colour_name);
-      return *quoted_cmd != 0
-                 ? strndup(quoted_cmd, text_buffer_size.get(*state))
-                 : nullptr;
-    }
-    /* [height],[width] [color1] [color2] */
-    g->scale = defscale;
-    if (sscanf(argstr, "%d,%d %s %s", &g->height, &g->width, first_colour_name,
-               last_colour_name) == 4) {
-      apply_graph_colours(g, first_colour_name, last_colour_name);
-      return *quoted_cmd != 0
-                 ? strndup(quoted_cmd, text_buffer_size.get(*state))
-                 : nullptr;
-    }
-    /* [command] [height],[width] [color1] [color2] [scale] */
-    if (sscanf(argstr, "%1023s %d,%d %s %s %lf", buf, &g->height, &g->width,
-               first_colour_name, last_colour_name, &g->scale) == 6) {
-      apply_graph_colours(g, first_colour_name, last_colour_name);
-      return strndup(buf, text_buffer_size.get(*state));
-    }
-    g->scale = defscale;
-    if (sscanf(argstr, "%1023s %d,%d %s %s", buf, &g->height, &g->width,
-               first_colour_name, last_colour_name) == 5) {
-      apply_graph_colours(g, first_colour_name, last_colour_name);
-      return strndup(buf, text_buffer_size.get(*state));
-    }
-
-    buf[0] = '\0';
-    g->height = default_graph_height.get(*state);
-    g->width = default_graph_width.get(*state);
-    if (sscanf(argstr, "%s %s %lf", first_colour_name, last_colour_name,
-               &g->scale) == 3) {
-      apply_graph_colours(g, first_colour_name, last_colour_name);
-      return *quoted_cmd != 0
-                 ? strndup(quoted_cmd, text_buffer_size.get(*state))
-                 : nullptr;
-    }
-    g->scale = defscale;
-    if (sscanf(argstr, "%s %s", first_colour_name, last_colour_name) == 2) {
-      apply_graph_colours(g, first_colour_name, last_colour_name);
-      return *quoted_cmd != 0
-                 ? strndup(quoted_cmd, text_buffer_size.get(*state))
-                 : nullptr;
-    }
-    if (sscanf(argstr, "%1023s %s %s %lf", buf, first_colour_name,
-               last_colour_name, &g->scale) == 4) {
-      apply_graph_colours(g, first_colour_name, last_colour_name);
-      return strndup(buf, text_buffer_size.get(*state));
-    }
-    g->scale = defscale;
-    if (sscanf(argstr, "%1023s %s %s", buf, first_colour_name,
-               last_colour_name) == 3) {
-      apply_graph_colours(g, first_colour_name, last_colour_name);
-      return strndup(buf, text_buffer_size.get(*state));
-    }
-
-    buf[0] = '\0';
-    first_colour_name[0] = '\0';
-    last_colour_name[0] = '\0';
-    if (sscanf(argstr, "%d,%d %lf", &g->height, &g->width, &g->scale) == 3) {
-      return *quoted_cmd != 0
-                 ? strndup(quoted_cmd, text_buffer_size.get(*state))
-                 : nullptr;
-    }
-    g->scale = defscale;
-    if (sscanf(argstr, "%d,%d", &g->height, &g->width) == 2) {
-      return *quoted_cmd != 0
-                 ? strndup(quoted_cmd, text_buffer_size.get(*state))
-                 : nullptr;
-    }
-    if (sscanf(argstr, "%1023s %d,%d %lf", buf, &g->height, &g->width,
-               &g->scale) < 4) {
-      g->scale = defscale;
-      // TODO(brenden): check the return value and throw an error?
-      sscanf(argstr, "%1023s %d,%d", buf, &g->height, &g->width);
-    }
-
-    if ((*quoted_cmd == 0) && (*buf == 0)) { return nullptr; }
-    return strndup(*quoted_cmd != 0 ? quoted_cmd : buf,
-                   text_buffer_size.get(*state));
   }
 
-  return nullptr;
+  /* all the following functions try to interpret the beginning of a
+   * a string with different format strings. If successful, they return from
+   * the function */
+
+  /* interpret the beginning(!) of the argument string as:
+   * '[height],[width] [color1] [color2] [scale]'
+   * This means parameters like -t and -l may not be in the beginning */
+  if (sscanf(argstr, "%d,%d %s %s %lf", &g->height, &g->width,
+             first_colour_name, last_colour_name, &g->scale) == 5) {
+    apply_graph_colours(g, first_colour_name, last_colour_name);
+    return true;
+  }
+  g->height = default_graph_height.get(*state);
+  g->width = default_graph_width.get(*state);
+  first_colour_name[0] = '\0';
+  last_colour_name[0] = '\0';
+  g->scale = defscale;
+
+  /* [height],[width] [color1] [color2] */
+  if (sscanf(argstr, "%d,%d %s %s", &g->height, &g->width, first_colour_name,
+             last_colour_name) == 4) {
+    apply_graph_colours(g, first_colour_name, last_colour_name);
+    return true;
+  }
+  g->height = default_graph_height.get(*state);
+  g->width = default_graph_width.get(*state);
+  first_colour_name[0] = '\0';
+
+  /* [height],[width] [scale] */
+  if (sscanf(argstr, "%d,%d %lf", &g->height, &g->width, &g->scale) == 3) {
+    return true;
+  }
+  g->height = default_graph_height.get(*state);
+  g->width = default_graph_width.get(*state);
+
+  /* [height],[width] */
+  if (sscanf(argstr, "%d,%d", &g->height, &g->width) == 2) { return true; }
+  g->height = default_graph_height.get(*state);
+  g->width = default_graph_width.get(*state);
+
+  /* [height], */
+  char comma;
+  if (sscanf(argstr, "%d%[,]", &g->height, &comma) == 2) { return true; }
+  g->height = default_graph_height.get(*state);
+
+  /* [color1] [color2] [scale] */
+  if (sscanf(argstr, "%s %s %lf", first_colour_name, last_colour_name,
+             &g->scale) == 3) {
+    apply_graph_colours(g, first_colour_name, last_colour_name);
+    return true;
+  }
+  first_colour_name[0] = '\0';
+  last_colour_name[0] = '\0';
+  g->scale = defscale;
+
+  /* [color1] [color2] */
+  if (sscanf(argstr, "%s %s", first_colour_name, last_colour_name) == 2) {
+    apply_graph_colours(g, first_colour_name, last_colour_name);
+    return true;
+  }
+
+  /* [scale] */
+  if (sscanf(argstr, "%lf", &g->scale) == 1) { return true; }
+
+  return true;
 }
 #endif /* BUILD_GUI */
 

src/specials.h

@@ -29,6 +29,7 @@
 #ifndef _SPECIALS_H
 #define _SPECIALS_H
 
+#include <tuple>
 #include "colours.h"
 
 /* special stuff in text_buffer */
@@ -92,7 +93,8 @@ const char *scan_bar(struct text_object *, const char *, double);
 const char *scan_gauge(struct text_object *, const char *, double);
 #ifdef BUILD_GUI
 void scan_font(struct text_object *, const char *);
-char *scan_graph(struct text_object *, const char *, double);
+std::pair<char *, size_t> scan_command(const char *);
+bool scan_graph(struct text_object *, const char *, double);
 void scan_tab(struct text_object *, const char *);
 void scan_stippled_hr(struct text_object *, const char *);
 

tests/CMakeLists.txt

@@ -18,6 +18,7 @@ set(test_srcs ${test_srcs} test-core.cc)
 set(test_srcs ${test_srcs} test-diskio.cc)
 set(test_srcs ${test_srcs} test-fs.cc)
 set(test_srcs ${test_srcs} test-gradient.cc)
+set(test_srcs ${test_srcs} test-graph.cc)
 set(test_srcs ${test_srcs} test-colours.cc)
 
 add_executable(test-conky test-common.cc ${test_srcs})

tests/test-graph.cc

@@ -0,0 +1,216 @@
+/*
+ *
+ * Conky, a system monitor, based on torsmo
+ *
+ * Any original torsmo code is licensed under the BSD license
+ *
+ * All code written since the fork of torsmo is licensed under the GPL
+ *
+ * Please see COPYING for details
+ *
+ * Copyright (c) 2005-2021 Brenden Matthews, Philip Kovacs, et. al.
+ *	(see AUTHORS)
+ * All rights reserved.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <tuple>
+#include "catch2/catch.hpp"
+#include "conky.h"
+#include "lua-config.hh"
+#include "specials.h"
+
+#ifdef BUILD_GUI
+
+#define SF_SHOWLOG (1 << 1)
+
+// Specific value doesn't matter, but we check if the same one comes back
+constexpr double default_scale = M_PI;
+
+constexpr double default_width = 0;
+constexpr double default_height = 25;
+
+struct graph {
+  int id;
+  char flags;
+  int width, height;
+  bool colours_set;
+  Colour first_colour, last_colour;
+  double scale;
+  char tempgrad;
+};
+
+static std::pair<struct graph, bool> test_parse(const char *s) {
+  struct text_object obj;
+  bool result = scan_graph(&obj, s, default_scale);
+  auto g = static_cast<struct graph *>(obj.special_data);
+  struct graph graph = *g;
+  free(g);
+  return {graph, result};
+}
+
+std::string unquote(const std::string &s) {
+  auto out = s;
+  out.erase(remove(out.begin(), out.end(), '\"'), out.end());
+  return out;
+}
+
+TEST_CASE("scan_graph correctly parses input strings") {
+  state = std::make_unique<lua::state>();
+  conky::export_symbols(*state);
+
+  SECTION("Trivial parse") {
+    auto [g, success] = test_parse("");
+
+    REQUIRE(g.width == default_width);
+    REQUIRE(g.height == default_height);
+  }
+
+  /* test parsing combinations of options */
+  const char *size_options[][2] = {{"30", "500"}, {"80", ""}, {"", ""}};
+  const char *color_options[][2] = {{"orange", "blue"},
+                                    {"#deadff", "#392014"},
+                                    {"000000", "000000"},
+                                    {"", ""}};
+  const char *scale_options[] = {"0.5", ""};
+
+  SECTION("subset of [height,width] [color1 color2] [scale] [-t] [-l]") {
+    for (auto size : size_options) {
+      for (auto colors : color_options) {
+        for (auto scale : scale_options) {
+          bool ends_at_first_size = false;
+
+          /* build an argument string by combining the selected options */
+          std::string s;
+          if (*size[0] != '\0') {
+            s += size[0];
+            s += ",";
+            if (*size[1] == '\0') {
+              /* if the size is just a height, it has to be the end of the
+               * argument string */
+              ends_at_first_size = true;
+            } else {
+              s += size[1];
+            }
+            s += " ";
+          }
+          if (!ends_at_first_size) {
+            s += colors[0];
+            s += " ";
+            s += colors[1];
+            s += " ";
+            s += scale;
+          }
+
+          /* parse the argument string */
+          auto [g, success] = test_parse(s.c_str());
+
+          printf("command: %s\n", s.c_str());
+
+          /* validate parsing of each component */
+          if (*size[0] == '\0') {
+            REQUIRE(g.width == default_width);
+            REQUIRE(g.height == default_height);
+          } else {
+            REQUIRE(g.height == atoi(size[0]));
+            REQUIRE(g.width == atoi(size[1]));
+          }
+
+          /* if second half of size is empty, no subsequent values should be
+           * set
+           */
+          if (ends_at_first_size) {
+            REQUIRE(g.colours_set == false);
+            continue;
+          }
+
+          if (*colors[0] == '\0') {
+            REQUIRE(g.colours_set == false);
+          } else {
+            REQUIRE(g.colours_set == true);
+            REQUIRE(g.first_colour == parse_color(colors[0]));
+            REQUIRE(g.last_colour == parse_color(colors[1]));
+          }
+
+          if (*scale == '\0') {
+            REQUIRE(g.scale == default_scale);
+          } else {
+            REQUIRE(g.scale == 0.5);
+          }
+
+          REQUIRE(g.flags == 0);
+          REQUIRE(g.tempgrad == 0);
+        }
+      }
+    }
+  }
+
+  SECTION("[height,width] [color1 color2] [scale] [-t] [-l]") {
+    auto [g, success] = test_parse("21,340 orange blue 0.5 -t -l");
+
+    REQUIRE(success);
+    REQUIRE(g.width == 340);
+    REQUIRE(g.height == 21);
+    REQUIRE(g.colours_set == true);
+    REQUIRE(g.scale == 0.5);
+    REQUIRE(g.flags == SF_SHOWLOG);
+    REQUIRE(g.tempgrad == true);
+  }
+
+  SECTION("-t location") {
+    {
+      auto [g, success] = test_parse("21,340 red blue 0.5");
+      REQUIRE(g.tempgrad == false);
+    }
+    {
+      auto [g, success] = test_parse("21,340 red blue 0.5");
+      REQUIRE(g.tempgrad == false);
+    }
+    {
+      auto [g, success] = test_parse("-t 21,340 red blue 0.5");
+      REQUIRE(g.tempgrad == true);
+    }
+    {
+      auto [g, success] = test_parse("21,340 -t red blue 0.5");
+      REQUIRE(g.tempgrad == true);
+    }
+  }
+}
+
+TEST_CASE("scan_command correctly parses input strings") {
+  SECTION("parse commands") {
+    const char *command_options[][2] = {{"\"foo bar\"", "foo bar"},
+                                        {"\"foo bar\"\tbaz", "foo bar"},
+                                        {"\"foo bar\"\nbaz", "foo bar"},
+                                        {"\"foo bar\" baz", "foo bar"},
+                                        {"one two", "one"},
+                                        {"\"ls -t\"", "ls -t"},
+                                        {"\"ls -t\" 4309", "ls -t"},
+                                        {"foo-test", "foo-test"},
+                                        {"foo-test a b c", "foo-test"},
+                                        {"", ""}};
+    for (auto [command, expected_parsed] : command_options) {
+      auto [parsed, len] = scan_command(command);
+      REQUIRE(std::string(parsed) == expected_parsed);
+      if (command[0] == '"') {
+        REQUIRE(len == strlen(expected_parsed) + 2);
+      } else {
+        REQUIRE(len == strlen(expected_parsed));
+      }
+    }
+  }
+}
+
+#endif /* BUILD_GUI */