Pypi existence check (#30)

* Add python_package_exists() function

* Poll pypi.org or compatible index to see if a package exists
* Returns non-zero on success

* Implements python_package_exists() in delivery_defer_packages()

* Implements python_package_exists() in delivery_defer_packages()

* Bugfix: Avoid incorrect package selection

* With large package lists that contain multiple packages starting with the same strstr() would pick the first match
* This adds a temporary name variable that strcmp() can check against.

* Message correction:

* Change "release" to "testing" in testing environment failure message

* Amend message to fit the flow of the output

* Disable outdated conda notifications

* The latest version isn't always the greatest. Don't give the end-user any ideas. Just use whatever the installer provides... quietly

* Rename python_package_exists to pip_index_provides

* Document the function prototype
* Add missing comments in micromamba structure

* Ensure the temporary output file does not linger

1 files changed, 74 insertions, 6 deletions

diff --git a/src/conda.c b/src/conda.c
index 6ed96c7..ff55f14 100644
--- a/src/conda.c
+++ b/src/conda.c
@@ -79,6 +79,73 @@ int pip_exec(const char *args) {
     return system(command);
 }
 
+int pip_index_provides(const char *index_url, const char *name, const char *version) {
+    char cmd[PATH_MAX] = {0};
+    char name_local[255];
+    char version_local[255] = {0};
+    char spec[255] = {0};
+
+    if (isempty((char *) name) < 0) {
+        // no package name means nothing to do.
+        return -1;
+    }
+
+    // Fix up the package name
+    strncpy(name_local, name, sizeof(name_local) - 1);
+    tolower_s(name_local);
+    lstrip(name_local);
+    strip(name_local);
+
+    if (version) {
+        // Fix up the package version
+        strncpy(version_local, version, sizeof(version_local) - 1);
+        tolower_s(version_local);
+        lstrip(version_local);
+        strip(version_local);
+        sprintf(spec, "==%s", version);
+    }
+
+    char logfile[] = "/tmp/STASIS-package_exists.XXXXXX";
+    int logfd = mkstemp(logfile);
+    if (logfd < 0) {
+        perror(logfile);
+        remove(logfile);    // fail harmlessly if not present
+        return -1;
+    }
+
+
+    int status = 0;
+    struct Process proc;
+    memset(&proc, 0, sizeof(proc));
+    proc.redirect_stderr = 1;
+    strcpy(proc.f_stdout, logfile);
+
+    // Do an installation in dry-run mode to see if the package exists in the given index.
+    snprintf(cmd, sizeof(cmd) - 1, "python -m pip install --dry-run --no-deps --index-url=%s %s%s", index_url, name_local, spec);
+    status = shell(&proc, cmd);
+
+    // Print errors only when shell() itself throws one
+    // If some day we want to see the errors thrown by pip too, use this condition instead:  (status != 0)
+    if (status < 0) {
+        FILE *fp = fdopen(logfd, "r");
+        if (!fp) {
+            remove(logfile);
+            return -1;
+        } else {
+            char line[BUFSIZ] = {0};
+            fflush(stdout);
+            fflush(stderr);
+            while (fgets(line, sizeof(line) - 1, fp) != NULL) {
+                fprintf(stderr, "%s", line);
+            }
+            fflush(stderr);
+            fclose(fp);
+        }
+    }
+    remove(logfile);
+    return proc.returncode == 0;
+}
+
 int conda_exec(const char *args) {
     char command[PATH_MAX];
     const char *mamba_commands[] = {
@@ -275,12 +342,13 @@ int conda_setup_headless() {
     }
 
     // Configure conda for headless CI
-    conda_exec("config --system --set auto_update_conda false");    // never update conda automatically
-    conda_exec("config --system --set always_yes true");            // never prompt for input
-    conda_exec("config --system --set safety_checks disabled");     // speedup
-    conda_exec("config --system --set rollback_enabled false");     // speedup
-    conda_exec("config --system --set report_errors false");        // disable data sharing
-    conda_exec("config --system --set solver libmamba");            // use a real solver
+    conda_exec("config --system --set auto_update_conda false");     // never update conda automatically
+    conda_exec("config --system --set notify_outdated_conda false"); // never notify about outdated conda version
+    conda_exec("config --system --set always_yes true");             // never prompt for input
+    conda_exec("config --system --set safety_checks disabled");      // speedup
+    conda_exec("config --system --set rollback_enabled false");      // speedup
+    conda_exec("config --system --set report_errors false");         // disable data sharing
+    conda_exec("config --system --set solver libmamba");             // use a real solver
 
     char cmd[PATH_MAX];
     size_t total = 0;