Dynamically allocate memory for system commands

2 files changed, 82 insertions, 42 deletions

diff --git a/src/lib/core/conda.c b/src/lib/core/conda.c
index 07128e6..fb7ee25 100644
--- a/src/lib/core/conda.c
+++ b/src/lib/core/conda.c
@@ -62,37 +62,38 @@ int micromamba(const struct MicromambaInfo *info, char *command, ...) {
 }
 
 int python_exec(const char *args) {
-    int result = -1;
     const char *command_base = "python ";
-    const size_t required_len = strlen(command_base) + strlen(args) + 1;
+    const char *command_fmt = "%s%s";
 
-    char *command = calloc(required_len, sizeof(*command));
+    const int len = snprintf(NULL, 0, command_fmt, command_base, args);
+    char *command = calloc(len + 1, sizeof(*command));
     if (!command) {
-        SYSERROR("Unable to allocate %zu bytes for command string", required_len);
-        return result;
+        SYSERROR("Unable to allocate %d bytes for command string", len);
+        return -1;
     }
-    snprintf(command, required_len, "%s%s", command_base, args);
+
+    snprintf(command, len + 1, command_fmt, command_base, args);
     msg(STASIS_MSG_L3, "Executing: %s\n", command);
 
-    result = system(command);
+    const int result = system(command);
     guard_free(command);
     return result;
 }
 
 int pip_exec(const char *args) {
-    int result = -1;
     const char *command_base = "python -m pip ";
-    const size_t required_len = strlen(command_base) + strlen(args) + 1;
+    const char *command_fmt = "%s%s";
 
-    char *command = calloc(required_len, sizeof(*command));
+    const int len = snprintf(NULL, 0, command_fmt, command_base, args);
+    char *command = calloc(len + 1, sizeof(*command));
     if (!command) {
-        SYSERROR("Unable to allocate %zu bytes for command string", required_len);
-        return result;
+        SYSERROR("Unable to allocate %d bytes for command string", len);
+        return -1;
     }
-    snprintf(command, required_len, "%s%s", command_base, args);
+    snprintf(command, len + 1, command_fmt, command_base, args);
     msg(STASIS_MSG_L3, "Executing: %s\n", command);
 
-    result = system(command);
+    const int result = system(command);
     guard_free(command);
     return result;
 }
@@ -199,7 +200,6 @@ int pkg_index_provides(int mode, const char *index, const char *spec) {
 }
 
 int conda_exec(const char *args) {
-    char command[PATH_MAX];
     const char *mamba_commands[] = {
             "build",
             "install",
@@ -224,9 +224,18 @@ int conda_exec(const char *args) {
         }
     }
 
-    snprintf(command, sizeof(command) - 1, "%s %s", conda_as, args);
+    const char *command_fmt = "%s %s";
+    const int len = snprintf(NULL, 0, command_fmt, conda_as, args);
+    char *command = calloc(len + 1, sizeof(*command));
+    if (!command) {
+        return -1;
+    }
+
+    snprintf(command, len + 1, command_fmt, conda_as, args);
     msg(STASIS_MSG_L3, "Executing: %s\n", command);
-    return system(command);
+    const int result = system(command);
+    guard_free(command);
+    return result;
 }
 
 static int conda_prepend_bin(const char *root) {
@@ -521,10 +530,8 @@ int conda_setup_headless() {
 }
 
 int conda_env_create_from_uri(char *name, char *uri, char *python_version) {
-    char env_command[PATH_MAX];
     char *uri_fs = NULL;
 
-
     // Convert a bare system path to a file:// path
     if (!strstr(uri, "://")) {
         uri_fs = calloc(strlen(uri) + strlen("file://") + 1, sizeof(*uri_fs));
@@ -553,17 +560,34 @@ int conda_env_create_from_uri(char *name, char *uri, char *python_version) {
     snprintf(spec, sizeof(spec) - 1, "- python=%s\n", python_version);
     file_replace_text(tempfile, "- python\n", spec, 0);
 
-    sprintf(env_command, "env create -n '%s' --file='%s'", name, tempfile);
-    int status = conda_exec(env_command);
+    const char *fmt = "env create -n '%s' --file='%s'";
+    int len = snprintf(NULL, 0, fmt, name, tempfile);
+    char *env_command = calloc(len + 1, sizeof(*env_command));
+    if (!env_command) {
+        return -1;
+    }
+
+    snprintf(env_command, len + 1, fmt, name, tempfile);
+    const int status = conda_exec(env_command);
     unlink(tempfile);
+    guard_free(env_command);
 
     return status;
 }
 
 int conda_env_create(char *name, char *python_version, char *packages) {
-    char env_command[PATH_MAX];
-    sprintf(env_command, "create -n %s python=%s %s", name, python_version, packages ? packages : "");
-    return conda_exec(env_command);
+    const char *fmt = "create -n %s python=%s %s";
+    const int len = snprintf(NULL, 0, fmt, name, python_version, packages ? packages : "");
+    char *env_command = calloc(len + 1, sizeof(*env_command));
+    if (!env_command) {
+        return -1;
+    }
+
+    snprintf(env_command, len + 1, fmt, name, python_version, packages ? packages : "");
+    const int result = conda_exec(env_command);
+    guard_free(env_command);
+
+    return result;
 }
 
 int conda_env_remove(char *name) {
diff --git a/src/lib/delivery/delivery_install.c b/src/lib/delivery/delivery_install.c
index 7c900cb..0009c04 100644
--- a/src/lib/delivery/delivery_install.c
+++ b/src/lib/delivery/delivery_install.c
@@ -190,7 +190,6 @@ int delivery_purge_packages(struct Delivery *ctx, const char *env_name, int use_
 
 int delivery_install_packages(struct Delivery *ctx, char *conda_install_dir, char *env_name, int type, struct StrList **manifest) {
     char command_base[PATH_MAX];
-    char pkgs[STASIS_BUFSIZ];
     const char *env_current = getenv("CONDA_DEFAULT_ENV");
 
     if (env_current) {
@@ -204,7 +203,6 @@ int delivery_install_packages(struct Delivery *ctx, char *conda_install_dir, cha
     }
 
     memset(command_base, 0, sizeof(command_base));
-    memset(pkgs, 0, sizeof(pkgs));
     strcat(command_base, "install");
 
     typedef int (*Runner)(const char *);
@@ -227,8 +225,8 @@ int delivery_install_packages(struct Delivery *ctx, char *conda_install_dir, cha
     }
 
     sprintf(command_base + strlen(command_base), " --extra-index-url 'file://%s'", ctx->storage.wheel_artifact_dir);
-    size_t args_alloc_len = STASIS_BUFSIZ + 1;
-    char *args = calloc(args_alloc_len, sizeof(*args));
+    size_t args_alloc_len = STASIS_BUFSIZ;
+    char *args = calloc(args_alloc_len + 1, sizeof(*args));
     if (!args) {
         SYSERROR("%s", "Unable to allocate bytes for command arguments");
         return -1;
@@ -297,20 +295,17 @@ int delivery_install_packages(struct Delivery *ctx, char *conda_install_dir, cha
                         }
                     }
 
-                    const size_t required_len = strlen(args) - strlen(info->name) - strlen(info->version) + 5 + 1;
-                    if (required_len + args_alloc_len > args_alloc_len) {
-                        args_alloc_len += required_len;
-                        char *tmp = realloc(args, args_alloc_len * sizeof(*args));
-                        if (!tmp) {
+                    const char *fmt_append = "%s '%s==%s'";
+                    const char *fmt = " '%s==%s'";
+                    const int required_len = snprintf(NULL, 0, fmt_append, args, req, info->version);
+                    if (required_len > (int) args_alloc_len) {
+                        if (grow(required_len, &args_alloc_len, &args)) {
+                            SYSERROR("Unable to allocate %d bytes for command arguments", required_len);
                             guard_free(args);
-                            SYSERROR("%s", "Unable to reallocate memory for args");
                             return -1;
                         }
-                        args = tmp;
                     }
-                    snprintf(args + strlen(args),
-                             required_len,
-                             " '%s==%s'", req, info->version);
+                    snprintf(args + strlen(args), required_len, fmt, req, info->version);
                 } else {
                     fprintf(stderr, "Deferred package '%s' is not present in the tested package list!\n", name);
                     guard_free(args);
@@ -318,9 +313,29 @@ int delivery_install_packages(struct Delivery *ctx, char *conda_install_dir, cha
                 }
             } else {
                 if (startswith(name, "--") || startswith(name, "-")) {
-                    sprintf(args + strlen(args), " %s", name);
+                    const char *fmt_append = "%s %s";
+                    const char *fmt = " %s";
+                    const int required_len = snprintf(NULL, 0, fmt_append, args, name);
+                    if (required_len > (int) args_alloc_len) {
+                        if (grow(required_len, &args_alloc_len, &args)) {
+                            SYSERROR("Unable to allocate %d bytes for command arguments", required_len);
+                            guard_free(args);
+                            return -1;
+                        }
+                    }
+                    sprintf(args + strlen(args), fmt, name);
                 } else {
-                    sprintf(args + strlen(args), " '%s'", name);
+                    const char *fmt_append = "%s '%s'";
+                    const char *fmt = " '%s'";
+                    const int required_len = snprintf(NULL, 0, fmt_append, args, name);
+                    if (required_len > (int) args_alloc_len) {
+                        if (grow(required_len, &args_alloc_len, &args)) {
+                            SYSERROR("Unable to allocate %d bytes for command arguments", required_len);
+                            guard_free(args);
+                            return -1;
+                        }
+                    }
+                    sprintf(args + strlen(args), fmt, name);
                 }
             }
         }
@@ -332,9 +347,10 @@ int delivery_install_packages(struct Delivery *ctx, char *conda_install_dir, cha
         }
 
         int status = runner(command);
+        guard_free(args);
+        guard_free(command);
         if (status) {
-            guard_free(args);
-            guard_free(command);
+            // fail quickly
             return status;
         }
     }