[micromamba] [mamba] Fix wrong download url for custom channels

libmamba/include/mamba/core/util_string.hpp

@@ -29,6 +29,15 @@ namespace mamba
      */
     const char* raw_str_or_empty(const char* ptr);
 
+    /**
+     * Return the common substring of two strings by blocks located between the '/' separator,
+     * and considering that the common substring would be located at the end of str1 (search from
+     * left to right).
+     * str1 is considered smaller than (or equal to) str2.
+     * cf. Channels use case.
+     */
+    std::string get_common_substr(std::string_view str1, std::string_view str2);
+
     /**
      * Safe non utf-8 wrapping of <cctype> (see its doc).
      */

libmamba/src/core/channel.cpp

@@ -537,10 +537,22 @@ namespace mamba
             // of the channel (e.g. -c testchannel/mylabel/xyz)
             // needs to result in `name = private/testchannel/mylabel/xyz`
             std::string combined_name = it->second.name();
-            if (name != combined_name && name.find('/') != std::string::npos)
+            if (combined_name != name)
             {
-                combined_name += "/";
-                combined_name += name.substr(name.find('/') + 1, std::string::npos);
+                // Find common string between `name` and `combined_name`
+                auto common_str = get_common_substr(combined_name, name);
+                // Combine names properly
+                if (common_str.empty())
+                {
+                    combined_name += "/" + name;
+                }
+                else
+                {
+                    // NOTE We assume that the `common_str`, if not empty, is necessarily at the
+                    // beginning of `name` and at the end of `combined_name` (I don't know about
+                    // other use cases for now)
+                    combined_name += name.substr(common_str.size());
+                }
             }
 
             return Channel(

libmamba/src/core/util_string.cpp

@@ -15,6 +15,27 @@
 
 namespace mamba
 {
+    /********************************************************
+     *  Implementation of Channels use case util function   *
+     *******************************************************/
+    std::string get_common_substr(std::string_view str1, std::string_view str2)
+    {
+        std::string common_str{ str1 };
+        while ((str2.find(common_str) == std::string::npos))
+        {
+            if (common_str.find('/') != std::string::npos)
+            {
+                common_str = common_str.substr(common_str.find('/') + 1);
+            }
+            else
+            {
+                common_str = "";
+                break;
+            }
+        }
+        return common_str;
+    }
+
     /****************************************
      *  Implementation of cctype functions  *
      ****************************************/

libmamba/tests/src/core/test_channel.cpp

@@ -346,6 +346,7 @@ namespace mamba
             auto& ctx = Context::instance();
             ctx.custom_channels = {
                 { "test_channel", "https://server.com/private/channels" },
+                { "random/test_channel", "https://server.com/random/channels" },
             };
             ChannelContext channel_context;
 
@@ -381,6 +382,22 @@ namespace mamba
                 CHECK_EQ(c.urls(), exp_urls);
             }
 
+            {
+                std::string value = "random/test_channel/pkg";
+                const Channel& c = channel_context.make_channel(value);
+                CHECK_EQ(c.scheme(), "https");
+                CHECK_EQ(c.location(), "server.com/random/channels");
+                CHECK_EQ(c.name(), "random/test_channel/pkg");
+                CHECK_EQ(c.canonical_name(), "random/test_channel/pkg");
+                CHECK_EQ(c.platforms(), std::vector<std::string>({ platform, "noarch" }));
+                std::vector<std::string> exp_urls(
+                    { std::string("https://server.com/random/channels/random/test_channel/pkg/")
+                          + platform,
+                      std::string("https://server.com/random/channels/random/test_channel/pkg/noarch") }
+                );
+                CHECK_EQ(c.urls(), exp_urls);
+            }
+
             ctx.channel_alias = "https://conda.anaconda.org";
             ctx.custom_channels.clear();
         }

libmamba/tests/src/core/test_util_string.cpp

@@ -385,6 +385,22 @@ namespace mamba
         {
             CHECK_EQ(concat("aa", std::string("bb"), std::string_view("cc"), 'd'), "aabbccd");
         }
+
+        TEST_CASE("get_common_substr")
+        {
+            CHECK_EQ(get_common_substr("", ""), "");
+            CHECK_EQ(get_common_substr("", "test"), "");
+            CHECK_EQ(get_common_substr("test", "test"), "test");
+            CHECK_EQ(get_common_substr("test/chan", "test/chan"), "test/chan");
+            CHECK_EQ(get_common_substr("test/chan/label", "label/abcd/xyz"), "label");
+            CHECK_EQ(get_common_substr("test/chan/label", "chan/label/abcd"), "chan/label");
+            CHECK_EQ(get_common_substr("test/chan/label", "abcd/chan/label"), "chan/label");
+            CHECK_EQ(get_common_substr("test", "abcd"), "");
+            CHECK_EQ(get_common_substr("test", "abcd/xyz"), "");
+            CHECK_EQ(get_common_substr("test/xyz", "abcd/xyz"), "xyz");
+            CHECK_EQ(get_common_substr("test/xyz", "abcd/gef"), "");
+            CHECK_EQ(get_common_substr("abcd/test", "abcd/xyz"), "");
+        }
     }
 
 }  // namespace mamba

mamba/mamba/utils.py

@@ -230,7 +230,8 @@ def get_base_url(url, name=None):
         tmp = url.rsplit("/", 1)[0]
         if name:
             if tmp.endswith(name):
-                return tmp.rsplit("/", 1)[0]
+                # Return base url stripped from name
+                return tmp[: -(len(name) + 1)]
         return tmp
 
     api_ctx.channel_alias = str(